AGRICULTURAL    ENGINEERING  SERIES 
E.  B.  McCORMICK,  CONSULTING  EDITOR 


FARM    MOTORS 


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PUBLISHERS     OF,    BOO  KS      F  O  R^ 

Coal  Age     ^     Electric  Railway  Journal 

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Chemical  6    Metallurgical  Engineering 

Electrical  Merchandising 


FARM    MOTORS 


STEAM  AND  GAS  ENGINES,  HYDRAULIC 

.AND  ELECTRIC  MOTORS,  TRACTION 

ENGINES,  AUTOMOBILES,  ANIMAL 

MOTORS,  WINDMILLS 


BY 


ANDREY  A.  POTTER 


MEMBER  AMERICAN  SOCIETY   OP  MECHANICAL  ENGINEERS,   DEAN   OF  THE   ENGINEERING 

DIVISION   AND   PROFESSOR   OF  STEAM   AND   GAS   ENGINEERING 

IN  THE   KANSAS  STATE   AGRICULTURAL  COLLEGE 


SECOND  EDITION 
THIRD  IMPRESSION 


McGRAW-HILL  BOOK  COMPANY,  INC. 

NEW  YORK:    239  WEST  39TH  STREET 

LONDON:    6  &  8  BOUVERIE  ST.,  E.  C.  4 

1913 


COPYRIGHT,  1913,  1917,  BY  THE 
McGRAW-HiLL  BOOK  COMPANY,  INC. 


MA.N 


PREFACE  TO  SECOND  EDITION 

The  first  edition  of  this  book  was  published  in  1913.  It  was 
new  in  its  field  and  the  experience  since  gained  in  teaching  farm 
motors  has  led  to  the  present  revision. 

In  this  edition  the  chapters  on  gas  and  oil  engines  and  on 
traction  engines  were  enlarged,  the  steam  engine  chapters  were 
rewritten  and  new  chapters  were  added  on  automobiles  and  on 
animal  motors.  All  other  chapters  were  revised. 

In  the  preparation  of  this  edition,  the  author  is  particularly 
indebted  to  President  J.  H.  Waters  and  to  his  colleagues  N.  A. 
Crawford,  W.  A.  Buck,  E.  V.  Collins  and  F.  A.  Wirt  of  the  Kan- 
sas State  Agricultural  College.  A.  A.  POTTER. 

MANHATTAN,  KANSAS, 
April  10,  1917. 


PREFACE 

In  preparing  this  book  it  has  been  the  intention  to  include  the 
fundamental  principles  governing  the  construction,  working  and 
management  of  motors  which  are  suitable  for  farm  use.  The 
motors  treated  include  steam  engines,  gas  and  oil  engines,  trac- 
tion engines,  automobiles,  water  motors,  windmills  and  electric 
motors. 

The  method  followed  in  each  chapter  was  to  give: 

1.  the  fundamental  principles  underlying  the  particular  motor, 

2.  the  principal  parts  of  the  motor, 

3.  auxiliary  parts, 

4.  uses  to  which  the  particular  type  of  motor  is  adapted. 

5.  selection,  erection  and  management  of  the  different  machines. 
While  this  book  was  prepared  primarily  as  a  text-book  for 

students  in  agricultural  engineering,  the  subject  matter  is  so  pre- 
sented that  it  will  be  of  equal  value  to  farmers  and  to  operators 
of  various  kinds  of  engines  and  motors.  Much  practical  informa- 
tion is  included  regarding  steam,  gas  and  electricity,  and  the  text 
is  illustrated  with  over  275  cuts. 

Some  space  is  devoted  to  the  more  refined  methods  used  in 
engineering  practice  for  improving  the  economy  of  various 
motors.  While  many  of  these  methods  are  not  used  at  the  pres- 
ent time  in  connection  with  farm  motors,  it  is  the  opinion  of  the 
author  that  a  knowledge  of  the  best  engineering  practice  is  not 
only  of  considerable  educational  value,  but  will  lead  to  the  more 
perfect  manipulation  of  the  simple  farm  motors. 

The  successful  rural  engineer  of  the  near  future  will  be  the 
man  that  applies  proven  engineering  to  the  machinery  and  con- 
structions used  on  the  farm. 

The  author  is  particularly  indebted  in  the  preparation  of  this 
book  to  Professors  E.  B.  McCormick,  M.  R.  Bowerman,  R.  A. 
Seaton,  and  W.  W.  Carlson,  of  the  Kansas  State  Agricultural 
College;  to  Professors  Allen  and  Bursley  of  the  University  of 
Michigan;  and  to  Mr.  S.  Yesner  of  Boston,  Mass. 

A.  A.  POTTER. 
MANHATTAN,  KANSAS, 
November,  1913. 

vii 


CONTENTS 

PAGE 

PREFACE .••."•'. v 

CHAPTER  I 

FARM  MOTORS  IN  GENERAL 1 

Sources  of  energy — Principles  governing  the  action  of  various 
mechanical  motors — Animal  motors — Comparison  of  various  types 
of  motors — Power  used  on  farms — Comparative  cost  of  power  with 
various  motors — Problems. 

CHAPTER  II 

FUNDAMENTAL  PRINCIPLES  AND  DEFINITIONS 6 

Matter — States  of  matter — Motion — Force  and  pressure — Work, 
energy  and  power — Horsepower — Indicated  horsepower — Brake 
horsepower — Draw-bar  horsepower — Nature  of  heat — Tempera- 
ture— Thermometers — Units  of  heat — Mechanical  equivalent  of 
heat— Specific  heat — Specific  gravity — Problems. 

CHAPTER  III 

STEAM  GENERATION  AND  STEAM  BOILERS    .    . 16 

Theory  of  steam  generation — Fuels — Combustion — Commercial 
value  of  fuels — Principal  parts  of  a  steam  power  plant — Classifica- 
tion of  boilers — Return  tubular  boiler — Vertical  fire-tube  boilers — 
Water-tube  boilers — Grates  for  boiler  furnaces — Piping  for  boilers 
— Pipe  fittings — Valves — Safety  valves — Steam  gages — Water  glass 
and  gage  cocks — Water  column — Steam  traps — Feed  pumps  and 
injectors — Feed-water  heaters — Chimneys  and  draft-producing 
systems — Firing — Rating  of  boilers — Management  of  boilers — 
Problems. 

CHAPTER  IV 

STATIONARY  STEAM  ENGINES 42 

Description  of  the  steam  engine — Action  of  the  plain  slide  valve — 
Types  of  steam  engine  valve  gears — Valve  setting — Steam  engine 
indicator  cards — Losses  in  steam  engines — Steam  engine  governors 
— Engine  details — Lubricators — Steam  separators — The  steam  lo- 
comotive or  Buckeymobile — Steam  turbines — Installation  and  care 
of  steam  engines — Problems. 

ix 


x  CONTENTS 

PAGE 

CHAPTER  V 
GAS  AND  OIL  ENGINES 65 

The  internal-combustion  engine — The  gas  engine  cycle — Classifica- 
tion of  gas  engines — The  four-stroke  cycle — The  two-stroke  cycle 
engine — Comparison  of  two-stroke  cycle  and  four-stroke  cycle 
engines — Gas  engine  fuels — Gasoline  and  other  distillates  of  crude 
petroleum — Alcohol  as  a  fuel  for  gas  engine  use — Essential  parts  of 
a  four-stroke  cycle  gas  engine — Carburetors  for  gasoline  engines — 
Carbureting  kerosene  and  the  heavier  fuels-^-Cooling  of  gas  engine 
cylinder  walls — Gas  engine  ignition  systems — Electric  ignition 
systems  for  gas  engines — The  make-and-break  system  of  ignition — 
The  jump  spark  system  of  ignition — Ignition  dynamos — Magnetos 
— Low-tension  magnetos — High-tension  magnetos — Timers — Auto- 
matic ignition  for  oil  engines — Lubrication  of  gas  and  oil  engines — 
Governing  of  gas  engines — The  gasoline  engine  on  the  farm — • 
Selecting  a  gas  engine — Installation  of  gas  engines — Instructions 
for  operating  gas  engines — Care  of  a  gas  engine — Problems. 

CHAPTER  VI 

AUTOMOBILES   . 122 

Types  of  automobiles — Essential,  parts  of  a  gasoline  automobile 
Automobile  motors — Clutches — Transmission  gears — The  progres- 
sive sliding-gear  transmission  system — The  selective  sliding-gear 
transmission  system — The  planetary  transmission  system — The 
friction  drive — Differentials  for  automobiles — Universal  joint — * 
Front  and  rear  axles — Steering  and  control  systems — Brakes — 
Wheels  and  tires — Carburetors  and  gasoline  feed  systems — Ignition 
— Automobile  lubrication — Automobile  starting  systems — Auto- 
mobile lighting  and  accessories — Management  of  automobiles— 
Gasoline  motor  cycles — Problems. 

CHAPTER  VII 

TRACTION  ENGINES 168 

Fundamental  parts  of  a  traction  engine — Steam  traction  engines — 
Boilers — Pumps — Feed-water  heaters — Engine  types — Reversing 
mechanisms  for  steam  traction  engines — Steering — Transmission 
systems  and  differentials — Gas  traction  engines — The  gas  traction 
engine  motor — Carburetors  for  traction  engines — Ignition  for  gas 
traction  engines — Transmission  systems  and  differentials — Type 
of  traction — Uses  of  traction  engines — Development  of  the  gas  trac- 
tion engine — Economy  of  gas  traction  engines — Rating  of  traction 
engines — Operation  and  care  of  traction  engines — Problems. 

CHAPTER  VIII 

WATER  MOTORS 211 

Determining  the  power  of  streams — Types  of  water  motors — Over- 


CONTENTS  xi 

PAGE 

shot,  undershot  and  breast  wheels — Impulse  water  motors — Water 
turbines^-The  hydraulic  ram — Problems. 

CHAPTER  IX 

WINDMILLS 221 

Types  of  windmills — Principal  parts  of  a  windmill — The  wind-wheel 
— The  rudder  or  vane — The  governor — Windmill  gearing — Wind- 
mill brake — Towers — Method  of  erecting  windmills — Care  of  wind- 
mills— Power  of  windmills — Uses  of  windmills — Problems. 

CHAPTER  X 

ELECTRIC  MOTORS,  GENERATORS  AND  BATTERIES 236 

Action  of  electricity — Units  of  electricity — Ohm's  law — Incandes- 
cent lamps — Wires  for  conductors  of  electricity — Electrical  batter- 
ies— Primary  batteries — Storage  batteries — The  lead  storage  bat- 
tery— The  Edison  storage  battery— Methods  of  connecting  bat- 
teries— The  electric  generator— Action  of  the  electric  generator — 
Direct  and  alternating  currents — Principal  parts  of  generators  and 
motors — Classification  of  generators  and  motors — Series-wound 
generators — Series-wound  motors — Shunt-wound  generators — 
Shunt-wound  motors — Compound-wound  generators — Compound- 
wound  motors — Various  types  of  motors  compared — Distribution  . 
of  electric  current — Electric  meters — Fuses  and  circuit  breakers — 
Switches  and  rheostats — Method  of  connecting  motors — The  elec- 
tric motor  on  the  farm — The  farm  electric  light  plant — Installation 
of  electric  motors  and  generators — Starting  and  stopping  motors — 
Starting  and  stopping  generators — Care  of  motors  and  generators 
— Problems. 

CHAPTER  XI 

ANIMAL  MOTORS 272 

The  horse — Selection  of  a  draft  horse — Capacity  and  power  of 
draft  animals — Selection  of  feed  for  the  horse — The  mule — The  ox 
— Cost  of  animal  power — Problems. 

CHAPTER  XII 

MECHANICAL  TRANSMISSION  OF  POWER 278 

Belts— Leather  belts— Rubber  belts— Canvas  belts— Care  of  belts 
— Method  of  lacing  belts — Pulleys — Method  of  calculating  sizes  of 
pulleys — Quarter-turn  belt — Chain  drives — Rope  transmission — 
Friction  gearing — Toothed  gearing — Shafting — Problems. 

INDEX  .  293 


FARM  MOTORS 

CHAPTER  I 
FARM  MOTORS  IN  GENERAL 

A  motor  is  an  apparatus  capable  of  doing  work.  Not  consid- 
ering animal  motors,  which  include  men,  horses  and  other  animals, 
the  mechanical  motors  available  for  farm  use  are:  heat  engines, 
including  steam,  gas,  oil,  hot-air  and  solar  engines;  pressure 
engines  such  as  waterwheels  and  water  motors;  windmills; 
electric  motors. 

Sources  of  Energy. — The  principal  source  of  all  energy  is 
the  sun.  It  causes  the  growth  of  plants  which  furnish  food 
for  man  and  animals.  The  great  coal  deposits  are  only  the 
result  of  the  storing  up  of  the  sun's  rays  in  plants  in  bygone 
days.  These  rays  are  also  responsible  for  the  raising  of  water 
from  sea  level  to  mountain  top,  thus  giving  it  energy  which  can 
be  utilized  to  turn  waterwheels  and  made  to  do  useful  work. 

On  the  other  hand,  while  the  sun's  rays  are  the  fundamental 
sources  of  all  energy,  they  can  be  utilized  directly  by  man  only 
to  a  very  limited  extent.  The  secondary  sources  of  energy  are 
the  wind,  waterfalls,  carbon  in  different  forms,  such  as  coal, 
petroleum,  or  gas,  and  chemicals  used  in  electric  batteries. 

Principles  Governing  the  Action  of  Various  Mechanical 
Motors. — All  mechanical  motors  do  work  by  virtue  of  motion 
given  to  a  piston,  to  blades  on  a  wheel,  or  to  an  armature  by  some 
substance  such  as  water,  steam,  gas,  air,  or  electricity.  The  first 
requirement  is  that  the  above-mentioned  substance,  often  called 
the  working  substance,  be  under  considerable  pressure. 

This  pressure  in  the  case  of  the  water  motor  or  waterwheel 
is  obtained  by  collecting  water  in  dams  and  tanks,  or  by  utilizing 
the  kinetic  energy  of  natural  waterfalls.  The  total  power 
available  in  water  when  in  motion  depends  on  the  weight  of  water 
discharged  in  a  given  time,  and  on  the  head  or  distance  through 

1 


which  the  water  is  allowed  to  fall.  The  head  of  water  can  be 
utilized  by  its  weight  or  pressure  acting  directly  on  a  piston  or 
on  blades  or  paddles  on  wheels. 

Considering  next  the  various  forms  of  heat  engines,  work  is 
accomplished  by  steam  or  gas  under  pressure,  this  pressure  being 
obtained  by  utilizing  the  heat  of  some  fuel  or  of  the  rays  of  the 
sun. 

A  motor  utilizing  the  heat  of  the  sun  is  called  a  solar  motor 
or  a  solar  engine.  The  action  of  this  type  of  motor  depends  on 
the  vaporization  of  water  into  steam  by  means  of  the  rays  of 
the  sun,  which  are  concentrated  and  intensified  by  means  -  of 
reflecting  surfaces. 

In  the  case  of  the  steam  engine  a  fuel,  like  coal,  oil,  or  gas,  is 
burned  in  a  furnace  and  its  heat  of  combustion  is  utilized  in 
changing  water  into  steam,  at  high  pressure,  in  a  special  vessel 
called  a  boiler.  This  high-pressure  steam  is  then  conveyed  by 
pipes  to  the  engine  cylinder  where  its  energy  is  expended  in 
pushing  a  piston  as  in  the  case  of  the  reciprocating  engine.  The 
sliding  motion  of  the  piston  may  be  changed  into  rotary  motion 
at  the  shaft  by  the  interposition  of  a  connecting  rod  and  crank. 
Another  method  is  to  allow  the  high-pressure  steam  to  escape 
through  a  nozzle,  strike  blades  on  a  wheel  and  produce  rotary 
motion  direct,  as  in  the  case  of  the  steam  turbine. 

In  another  type  of  heat  engine,  called  a  hot-air  engine,  air  is 
heated  in  a  cylinder  by  a  fuel  which  is  burned  outside  of  the  en- 
gine cylinder,  and  by  its  expansion  drives  a  piston  and  thus  does 
work. 

In  the  case  of  gas  and  oil  engines  the  fuel,  which  must  be  in  a 
gaseous  form  as  it  enters  the  engine  cylinder,  is  mixed  with  air 
in  the  proper  proportions  to  form  an  explosive  mixture.  It  is 
then  compressed  and  ignited  within  the  cylinder  of  the  engine, 
the  high  pressures  produced  by  the  explosion  pushing  on  a  piston 
and  doing  work.  These  engines  belong  to  a  class  called  internal- 
combustion  engines,  and  differ  from  the  steam  and  hot-air 
engines,  which  are  sometimes  called  external-combustion  en- 
gines, in  that  the  fuel  with  air  is  burned  inside  the  engine  cylinder, 
instead  of  in  an  auxiliary  apparatus. 

The  windmill  derives  its  high  pressure  for  doing  work  from  the 
moving  atmosphere. 


FARM  MOTORS  IN  GENERAL  3 

The  electric  motor  converts  electrical  energy  at  high  pressure 
into  work;  this  electrical  pressure  or  voltage  is  produced  in  an 
apparatus  called  an  electrical  dynamo,  or  generator. 

Animal  Motors. — The  animal  can  be  considered  as  a  motor  to 
which  fuel  is  supplied  in  the  form  of  food.  This  food  furnishes 
energy  required  for  the  operation  and  maintenance  of  the 
various  organs  and  processes  within  the  animal  body,  as  well 
as  for  the  production  of  mechanical  work.  The  animal  body  is, 
in  fact,  a  combination  of  complex  mechanisms,  in  every  one  of 
which  heat  is  produced  and  work  is  performed. 

Comparison  of  Various  Types  of  Motors. — The  solar  motor 
is  but  little  used  on  account  of  its  high  first  cost  and  great  bulk 
in  relation  to  the  small  power  developed. 

In  localities  where  the  wind  is  abundant  and  little  power  is 
needed,  the  windmill  is  the  most  desirable  and  cheapest  power. 
The  greatest  application  of  windmills  is  for  the  pumping  of  water 
for  residences  and  farms,  and  for  such  other  work  as  does  not 
suffer  from  suspension  during  calm  weather.  Electric  storage 
and  lighting  on  a  small  scale  from  the  power  of  a  windmill  has 
been  tried  in  several  places  with  fair  success,  but  probably  will 
not  be  adapted  to  any  great  extent  on  account  of  the  high  first 
cost  of  such  an  installation. 

The  water  motor  or  water  turbine  is  very  economical  if  a 
plentiful  supply  of  water  can  be  had  at  a  fairly  high  head,  but  its 
reliability  is  affected  by  drought,  floods  and  ice  in  the  water 
supply. 

The  hot-air  engine,  while  not  economical  in  fuel  consumption, 
is  well-adapted  for  pumping  water  in  places  where  the  cost  of 
fuel  is  not  an  important  item  and  where  safety  and  simplicity  of 
mechanism  are  essential.  The  hot-air  engine,  on  account  of  its 
high  cost,  bulk  and  poor  fuel  economy,  has  been  largely  super- 
seded by  the  oil  engine,  which  uses  gasoline  or  the  heavier  oils. 

Of  the  other  forms  of  heat  engines,  the  internal-combustion 
engine,  whether  using  gas  or  oil,  is  well-adapted  for  small  and 
medium-sized  powers,  such  as  for  farm  use  and  irrigation  work. 
The  oil  traction  engine  has  also  a  very  important  field  on  the 
modern  farm. 

For  the  generation  of  electricity,  and  in  large  sizes,  the  steam 
engines  or  steam  turbines  will  be  found  more  suitable  on  account 


4  FARM  MOTORS 

of  their  lower  first  cost  and  great  reliability.  The  steam  engine 
is  also  used  successfully  on  large  traction  engines. 

If  a  source  of  electric  current  is  available  at  a  low  price,  the 
electric  motor  is  very  desirable,  as  it  requires  little  care  and  can 
be  bought  in  sizes  to  suit  all  requirements. 

Of  the  animal  motors,  the  horse  is  the  most  important.  Unlike 
mechanical  motors,  the  horse  is  self-feeding,  self-reproducing 
and  self-maintaining.  For  very  short  intervals,  animal  motors 
are  capable  of  considerable  overload  capacity,  but  are  expensive, 
require  constant  care  and  can  work  effectively  only  for  short 
periods  of  time.  With  animal  motors,  the  amount  of  power  under 
the  control  of  one  man  is  much  less  than  in  the  case  of  me- 
chanical motors.  The  mechanical  motor  requires  fuel  only  when 
actively  at  work,  while  the  animal  motor  requires  feed  at  regular 
intervals  whether  working  or  not. 

Power  Used  on  Farms. — About  25  million  horses  and  mules 
are  available  for  power  purposes  on  the  farms  of  the  United 
States.  This  represents  available  animal  power  to  the  amount  of 
about  16  million  horsepower.  The  power  available  in  mechanical 
farm  motors  will  probably  exceed  10  million  horsepower.  The 
total  amount  of  power  used  on  farms  thus  represents  more  than 
25  million  horsepower,  or  the  power  which  is  available  on  farms  is 
about  one-third  greater  than  the  total  amount  of  power  used  by 
all  the  manufacturing  industries  of  this  country. 

Comparative  Cost  of  Power  with  Various  Motors. — Varying 
character  and  prices  of  both  feed  for  animal  motors  and  fuel 
for  mechanical  motors  will  affect. -the  cost  of  power  in  different 
localities.  Ordinarily,  the  power  produced  by  animal  motors  is 
more  expensive  than  that  developed  by  the  use  of  mechanical 
motors.  Experiments  indicate  that  with  the  horse  as  a  motor, 
the  cost  of  power  per  horsepower  per  hour  will  vary  from  5 
to  6^  cts.  With  stationary  gasoline  engines,  the  cost  of  power 
will  vary  from  1%  to  2J4  cts.  per  horsepower  per  hour;  with 
kerosene  fuel,  from  %  to  1  ct. ;  with  fuel  oil,  less  than  1  ct.  per 
horsepower  per  hour.  With  steam  engines  a  horsepower  per  hour 
can  usually  be  produced  for  about  1  ct. 

Problems:  Chapter  I 

1.  What  is  a  motor?     Name  four  types  of  mechanical  motors. 

2.  Name  the  principal  source  of  all  energy.     Explain  in  detail, 


FARM  MOTORS  IN  GENERAL  5 

3.  What  are  the  fundamental  principles  which  govern  the  action  of  vari- 
ous mechanical  motors?     Illustrate  how  the  principle  is  applied  in  the  case 
of  waterwheels,  steam  engines,  gas  engines,  windmills,  electric  motors. 

4.  Compare  various  types  of  mechanical  motors  as  to  their  adaptability 
for  use  on  the  farm. 

6.  Discuss  the  relative  advantages  and  disadvantages  of  mechanical 
motors  and  of  animal  motors. 

6.  How  does  the  power  available  on  American  farms  compare  with  the 
power  used  in  the  manufacturing  industries  of  this  country? 


CHAPTER  II 
FUNDAMENTAL  PRINCIPLES  AND  DEFINITIONS 

Before  a  study  is  made  of  any  motor,  the  fundamental  concep- 
tions of  physics  regarding  states  of  matter,  work,  power  and  heat 
are  essential. 

Matter. — Matter  is  that  which  occupies  space  and,  when 
limited  in  amount,  it  is  called  a  body.  Matter  in  any  form  con- 
sists of  a  great  many  small  particles,  called  molecules,  the 
relative  position  of  which  determines  the  state  in  which  a  sub- 
stance exists. 

States  of  Matter. — Matter  exists  in  the  solid,  liquid  and  gase- 
ous states. 

In  the  case  of  the  solid  the  relative  positions  of  the  molecules  are 
fixed.  A  '-solid  having  a  certain  shape  or  form,  whether  due  to 
natural  or  artificial  causes,  will  retain  that  form,  unless  and  until 
it  is  made  to  change  the  same  by  some  external  cause. 

In  the  liquid,  the  relative  positions  of  the  various  .molecules 
are  not  fixed.  The  shape  or  form  of  a  liquid  depends,  therefore, 
on  the  solid  walls  surrounding  it,  a  liquid  assuming  the  form  of 
any  vessel  in  which  it  may  be  placed. 

In  the  case  of  a  gas  the  various  molecules  struggle  to  occupy 
greater  space.  A  gas  can  be  greatly  compressed  by  an  external 
force,  and  will  expand  to  a  considerable  extent,  if  it  is  given  perfect 
freedom. 

Motion. — Motion  means  change  of  place.  If  a  definite  amount 
of  matter,  called  a  body,  is  removed  from  one  place  to  another, 
motion  is  produced. 

Force  and  Pressure. — Anything  which  produces  or  tends  to 
produce,  modifies  or  tends  to  modify  motion  is  called  force. 
Force  is  measured  in  pounds.  Pressure  is  the  intensity  of  force 
and  is  equal  to  the  total  force  divided  by  the  area  over  which  it 
acts.  For  example,  a  force  of  1,000  Ib.  acting  on  a  body  whose 
dimensions  are  5  by  2  in.,  will  produce  a  pressure  or  intensity 
of  force  equal  to  the  force  divided  by  the  area  of  the  body  in 

1  000 
square  inches,  or    '        =  100  Ib.     In  English  and  American  prac- 


PRINCIPLES  AND  DEFINITIONS  7 

tice,  pressure  is  always  expressed  in  pourids  per  square  inch. 
Thus  when  a  steam  gage  on  a  boiler  is  registering  80  lb.,  this 
means  that  the  steam  is  capable  of  transmitting  a  force  of  80  lb. 
for  every  square  inch  on  which  it  acts.  If  it  is  allowed  to  act  on 
a  12-in.  piston,  the  area  of  which  is  113.1  sq.  in.,  the  total  force 
exerted  on  the  piston  is  80  times  113.1  or  9,048  lb. 

The  pressure  exerted  by  the  atmosphere  is  called  barometric 
pressure.  The  barometric  pressure  is  14.7  lb.  per  square  inch  at 
sea  level  and  decreases  as  the  altitude,  or  the  height  of  the  sur- 
face of  the  earth  above  sea  level,  increases.  For  each  2,000  ft. 
in  elevation  the  pressure  of  the  atmosphere  is  decreased  by  about 
1  lb.  The  barometric  pressure  plus  gage  pressure  equals  absolute 
pressure. 

Work,  Energy  and  Power. — Work  means  force  times  distance 
through  which  it  acts  and  is  independent  of  time.  If  a  body  of 
1  lb.  is  raised  through  a  distance  of  1  ft.,  the  resulting  work  is 
1  ft.-lb. 

The  capacity  for  doing  work  is  called  energy.  Energy  exist- 
ing in  a  body  at  rest,  as  in  the  case  of  the  raised  weight,  is  called 
potential  energy.  Energy  possessed  by  a  body  when  in  motion 
is  called  kinetic  energy. 

As  an  illustration,  a  cubic  foot  of  water,  weighing  62.5  lb. 
when  at  rest  at  a  height  of  100  ft.,  has  potential  energy  of  6,250 
ft.-lb.  and  this  potential  energy  is  changed  into  kinetic  energy 
of  work  when  the  water  is  allowed  to  fall  through  that  height. 
The  water  in  the  above  example  when  allowed  to  fall  through  10 
ft.  will  be  capable,  on  account  of  its  kinetic  energy,  to  do  625  ft.- 
lb.  of  work  and  will  have  a  potential  energy  of  6,250  —  625,  or 
5,625  ft.-lb.  when  it  comes  again  to  rest. 

Power  takes  into  consideration  the  time  required  to  do  a  certain 
amount  of  work  and  is  denned  as  the  rate  of  doing  work.  Thus 
if  steam  at  a  pressure  of  100  lb.  moves  a  piston  18  in.  in  diameter 
through  a  distance  of  2  ft.,  the  work  done  is  100  times  508.92 
(the  area  of  the  piston  in  inches  multiplied  by  the  distance  in 
feet)  or  50,892  ft.-lb.  The  power  of  the  engine,  however,  de- 
pends on  the  time  that  the  steam  requires  to  move  the  piston 
through  the  given  distance  and,  if  the  motion  is  accomplished 
in  1  sec.,  the  power  of  the  engine  is  five  times  greater  than  if 
5  sec.  were  required. 


8  FARM  MOTORS 

Horsepower. — If  work  is  done  at  the  rate  of  33,000  ft.-lb. 
per  minute,  1  hp.  is  said  to  be  exerted.  This  means  that  an 
engine  will  have  a  capacity  of  1  hp.  if  it  can  do  550  ft.-lb.  of 
work  in  a  second,  33,000  ft.-lb.  of  work  in  a  minute,  or  1,980,000 
ft.-lb.  of  work  in  an  hour.  To  determine  the  horsepower  de- 
veloped by  any  motor  or  engine,  it  is  necessary  to  find  the  foot- 
pounds of  work  which  the  motor  or  engine  is  doing  in  a  minute 
and  divide  this  by  33,000.  In  the  example  of  the  previous  para- 
graph if  the  piston  passes  through  the  distance  of  2  ft.  in  J£o 
min.,  the  power  of  the  engine  in  horsepower  is 

25,446  X  2 
33,000  X  -fr- 
it is  important  to  remember  that  power  takes  into  considera- 
tion work  and  time.     All  animals,  including  man,  are  able  to 
produce  more  power  for  a  short  period  of  time,  while  mechanical 
motors,  whether  driven  by  water,  wind,  steam,  gas,  or  electricity 
can  exert,  with  proper  care,  the  power  for  which  they  are  designed 
for  an  indefinite  length  of  time. 

Indicated  Horsepower. — The  term  "indicated  horsepower" 
(i.hp.)  is  applied  to  the  rate  of  doing  work  by  steam  or  by  a  gas 
in  the  cylinder  of  an  engine,  and  is  obtained  by  means  of  a 
special  instrument,  called  an  indicator.  One  form  of  this  type 
of  instrument,  the  Crosby,  is  shown  in  section  in  Fig.  1.  It 
consists  essentially  of  a  cylinder  (4),  which  is  placed  in  direct 
communication  with  the  engine  cylinder,  and  in  which  moves  a 
piston  (8)  compressing  a  spring  above  it  and  raising  the  arm  (16). 
At  the  end  of  the  arm  is  a  pencil  (23)  which  records  graphically  the 
pressure  of  the  steam  in  the  engine  cylinder  on  the  revolving 
drum  (24).  This  drum  (24)  is  covered  with  paper  and  receives  its 
motion  from  the  engine  crosshead.  From  the  diagram  drawn 
on  the  drum  of  the  indicator,  the  average  unbalanced  pressure 
is  determined,  and  the  horsepower  is  calculated  from  this  and 
from  dimensions  and  speed  of  the  engine. 

As  an  illustration:  Given  the  average  unbalanced  pressure  of 
the  steam  on  a  12-in.  piston,  as  obtained  by  means  of  an  indicator, 
and  called  the  mean  effective  pressure,  40  Ib.  per  square  inch; 
then  the  total  pressure  exerted  by  the  steam  is 

Total  pressure  =  40  X  113.1  =  4,524  Ib. 


PRINCIPLES  AND  DEFINITIONS 


9 


If  the  stroke  of  the  piston  is  13  in.,  the  work  done  in  foot-pounds 
per  stroke  is 

10 

4,524  X  j|  =  4,901 

If  the  engine  speed  is  250  r.p.m.,  the  work  per  minute  will  be, 
if  the  engine  is  single  acting, 

4,901  X  250  =  1, 225,250  ft.-lb. 


FIG.  1. — Steam  engine  indicator. 

Since  33,000  ft.-lb.  per  minute  is  1  hp.,  the  power  of  the  engine 
when  single-acting  is 

1,225,250  =          . 


As  steam  engines  are  usually  double-acting,  an  indicator  card 
would  have  to  be  taken  of  the  crank  end,  the  unbalanced  or  the 
mean  effective  pressure  determined  for  that  end  and  the  indicated 
horsepower  calculated  by  the  above  method,  taking  into  considera- 
tion the  size  of  the  piston  rod.  The  total  indicated  horsepower 
of  the  engine  is  the  sum  of  that  calculated  for  the  two  ends. 


10 


FARM  MOTORS 


Brake  Horsepower. — Brake  horsepower  represents  the  actual 
effective  power  which  a  motor  or  engine  can  deliver  for  the  pur- 
pose of  work  at  a  shaft  or  a  brake,  or  transmit  to  a  belt  for 
stationary  work,  such  as  threshing  or  the  driving  of  machines. 
An  instrument  for  the  measurement  of  the  brake  horsepower  of 
motors,  and  called  a  Prony  brake,  is  shown  in  Fig.  2.  This  brake 
consists  of  two  wooden  blocks  BB  which  fit  around  the  pulley  P 


FIG.  2. — Prony  brake. 

and  are  tightened  by  means  of  the  thumb  nuts  NN.  A  projec- 
tion of  one  of  the  blocks,  the  lever  L,  rests  on  the  platform  scale 
S.  When  the  brake  is  balanced,  the  power  absorbed  is  measured 
by  the  weight  as  registered  on  the  scales,  multiplied  by  the 
distance  it  would  pass  through  in  that  time  if  free  to  move.  If 
Z  is  the  length  of  the  brake  arm  in  feet,  w  the  weight  as  registered 
on  the  scales,  in  pounds,  and  n  the  revolutions  per  minute  of 
the  motor,  the  horsepower  absorbed  can  be  calculated  by  the 
formula 

Brake  horsepower  =  00  „„, 

oo,UUU 

As  an  illustration,  the  scale  reading  of  an  engine  running  at  250 
r.p.m.  is  80  Ib.  If  the  length  of  the  brake  arm  is  5>^  ft.,  calculate 
the  brake  horsepower  developed. 


Brake  horsepower 


2  X  3.1416  X  5.25  X  80  X 
33,000 


=  20.00 


Drawbar   Horsepower. — The   belt   or  the  brake  horsepower 
minus  the  power  required  to  propel  the  weight  of  a  traction  engine 


PRINCIPLES  AND  DEFINITIONS  11 

or  power  vehicle  is  called  the  drawbar  horsepower.  Ordinarily, 
a  traction  engine  will  require  about  50  per  cent,  of  the  total 
power  developed  by  its  motor,  to  move  the  traction  engine.  This 
means  that  the  drawbar  horsepower,  available  for  plowing  or  for 
pulling  implements,  is  about  one-half  of  the  total  power  developed 
by  the  motor. 

Nature  of  Heat. — Heat  is  a  form  of  energy  and  not  a  material 
substance.  The  heat  of  a  body  depends  on  the  vibratory  motion 
of  the  particles  or  molecules  of  which  the  body  is  built  up;  the 
greater  the  rate  of  motion  of  these  molecules  the  higher  is  the 
temperature  of  the  body. 

Temperature. — Temperature  indicates  the  relative  heats  of 
bodies,  or  the  relative  rates  of  motion  of  the  molecules  in  bodies. 
Temperature  is  not  a  measure  of  the  amount  or  quantity  of 
heat  in  a  body.  Thus  a  small  and  a  large  piece  of  metal  may  be 
heated  to  the  same  temperature,  but  the  large .  piece  would 
possess  the  greater  quantity  of  heat.  Temperature  is  an  indica- 
tion of  the  sensible  heat  of  a  substance,  or  the  heat  intensity 
which  can  be  revealed  to  the  senses  of  an  observer. 

Thermometers. — A  thermometer  is  an  instrument  -by  means  of 
which  the  temperature  of  a  substance  is  measured.  As  usually 
constructed,  it  consists  of  a  liquid  such  as  mercury  or  alcohol 
inclosed  in  a  bulb  at  one  end  of  a  thin  glass  tube,  the  temperature 
changes  producing  sufficient  variations  in  the  expansion  of  the 
liquid  to  be  read  off  on  a  scale  attached  to,  or  graduated  on,  the 
glass  tube. 

Thermometers  are  graduated  in  three  different  ways,  which  are 
called  the  three  thermometric  scales,  the  type  of  scale  depending 
on  the  number  of  graduations,  or  degrees  (°  denotes  degree), 
between  the  melting-point  of  ice  and  the  boiling-point  of  water. 

The  scale  mostly  used  in  English-speaking  countries  is  the 
Fahrenheit  (F.).  In  this  case  the  melting-point  of  ice  is  taken 
at  32°  and  the  boiling-point  of  water  at  212°.  Thus  the  Fahren- 
heit degree  (°F.)  is  J^go  of  the  interval  between  the  two  fixed 
points. 

In  scientific  work  the  Centigrade  scale  is  used  in  most  countries. 
The  Centigrade  degree  is  Koo  of  the  temperature  interval 
between  the  melting-point  of  ice  and  the  boiling-point  of  water, 
these  two  fixed  points  being  denoted  0°C.  and  100°C.  respectively. 


12  FARM  MOTORS 

Another  scale,  used  only  to  a  limited  extent  in  certain  countries 
of  Europe  is  the  Reaumur  scale,  which  has  the  melting-point  of 
ice  at  0°R.  and  the  boiling-point  of  water  at  80°R. 
.  The  relations  existing  between  the  thermometric  scales  mostly 
used,  i.e.,  the  Fahrenheit  (F.)  and  the  Centigrade  (C.),  can  be 
expressed : 

degrees  C.  =  %  (degrees  F.  -32) 
degrees  F.  =  %  degrees  C.  +32 

Example:  Convert  15°C.  to  the  Fahrenheit  scale  and  400°F. 
to  the  Centigrade  scale. 

degrees  F.  =  %  X  degrees  C.  +32 
=  %  X  15  +  32 
=  27  +  32  =  59°F. 
degrees  C.  =  %  (degrees  F.  —32) 
=  %  (400  -  32) 
=  204°C. 

Table  1  can  be  used  for  converting  Centigrade  into  Fahrenheit 
degrees  and  conversely. 

Units  of  Heat. — Heat  is  measured  in  heat  units.  A  heat  unit 
is  the  amount  of  heat  required  to  raise  the  temperature  of  1 
Ib.  of  water  1°.  The  heat  unit  used  in  English-speaking  countries 
is  the  British  thermal  unit  (B.t.u.).  The  B.t.u.  is  denned  as  the 
amount  of  heat  required  to  raise  1  Ib.  of  water  from  62°F.  to 
63°F. 

When  a  certain  illuminating  gas  is  said  to  contain  600  B.t.u., 
this  means  that  each  cubic  foot  of  the  gas  is  capable  of  raising 
the  temperature  of  10  Ib.  of  water  through  60°F.,  or  that  it  will 
raise  the  temperature  of  water  so  that  the  product  of  the  weight 
of  water  and  temperature  rise  (in  °F.)  is  600. 

Mechanical  Equivalent  of  Heat. — It  has  been  proven  experi- 
mentally that  heat  and  work  are  mutually  convertible.  It  re- 
quires 778  ft.-lb.  of  work  to  produce  1  B.t.u. ;  and  similarly  1  B.t.u. 
will  produce  778  ft.-lb.  of  work,  if  all  the  heat  is  converted  into 
work.  The  number  778  is  called  the  mechanical  equivalent  of 
heat.  It  is  due  to  the  fact  that  heat  can  be  converted  into  work 
that  the  various  heat  engines,  including  the  steam,  gas  and  oil 
engines,  are  possible. 

Specific  Heat. — As  the  addition  of  the  same  quantity  of  heat 
will  not  produce  the  same  temperature  changes  in  equal  weights 


PRINCIPLES  AND  DEFINITIONS 


13 


TABLE  1. — RELATION  BETWEEN  THE  FAHRENHEIT  AND  CENTIGRADE  THER- 

MOMETRIC  SCALES 


Fahr, 

Cent. 

Fahr.  " 

Cent. 

-30 

-34.4 

210 

98.9 

-20 

-28.9 

212 

100.0 

-10 

-23.3 

220 

104.4 

0 

-17.8 

230 

110.0 

+10 

-12.2 

240 

119.6 

20 

-  6.7 

250 

121.1 

30 

-  1.1 

260 

126.7 

32 

0.0 

270 

132.2 

40 

+  4.4 

280 

137.8 

50 

10.0 

290 

143.3 

60 

15.6 

300 

148.9 

70 

21.1 

310 

154.4 

80 

26.7 

320 

160.0 

90 

32.2 

330 

165.6 

100 

37.8 

340 

171.1 

110 

43.3 

350 

176.7 

120 

48.9 

360 

182.2 

130 

54.4 

370 

187.8 

140 

60.0 

380 

193.3 

150 

65.6 

390 

198.9 

160 

71.1 

400 

204.4 

170 

76.7 

410 

210.0 

180 

82.2 

420 

215.6 

190 

87.8 

430 

221.1 

200 

93.3 

440 

226.7 

of  different  substances,  it  is  evident  that  the  amount  of  heat 
which  can  be  taken  in  or  given  out  by  any  substance  depends  on 
the  capacity  of  that  substance  for  heat.  The  capacity  of  a  sub- 
stance for  heat,  or  the  resistance  which  a  substance  offers  to  a 
change  in  its  temperature,  is  called  its  specific  heat.  The 
specific  heat  of  water  is  taken  as  the  standard  and  equal  to  one. 
Specific  Gravity. — By  specific  gravity  is  meant  the  relation 
existing  between  the  weight  of  any  substance  and  the  weight  of 
an  equal  volume  or  bulk  of  water.  Thus  the  specific  gravity 
of  cast  iron  is  about  7,  which  means  that  a  cubic  foot  of  iron  is 
seven  times  heavier  than  a  cubic  foot  of  water.  In  Table  2 
are  given  the  specific  heats  and  specific  gravities  of  common 
substances. 


14 


FARM  MOTORS 


TABLE  2. — SPECIFIC   HEATS  AND  SPECIFIC   GRAVITIES  OF  COMMON 

SUBSTANCES 


Name  of  substance 

Specific  heat 
(average) 

Specific  gravity 
(average) 

Solids 
Iron,  cast         •  

0  .  1298 

7  2100 

Iron  wrought 

0  1138 

7  7000 

Steel  

0.1170 

7  .  8000 

Lead         

0.0314 

11  4000 

Copper.  , 

0.0951 

8.9000 

Glass  

0.1700 

2.6000 

Ice                                                 .    . 

0  .  5040 

0  .  9000 

Stone 

0  2100 

2  7500 

Brickwork,  masonry  

0.2000 

2.0000 

Liquids 
Water  

1  .  0000 

1.0000 

Kerosene.  . 

0  .  4750 

0.8100 

Gasoline  

0.5350 

0.6900 

Alcohol,  ethyl   

0.5500 

0.7900 

Alcohol,  methyl                                  .  . 

0.5900 

0.8080 

Ammonia 

0  9500 

Vegetable  oil  

0.4000 

0.9000 

Gases           * 
Air  

0.2375 

1.0000 

Oxygen                                .          ...... 

0.2175 

1.1052 

Hydrogen 

3  .  4090 

0  0692 

Nitrogen  

0.2438 

0.9701 

Ammonia.  ...                                   .... 

0.5080 

0.5889 

Problems:  Chapter  II 

1.  Calculate  the  work  done  by  a  pump  when  lifting  100  gal.  of  water 
to  a  height  of  125  ft. 

2.  The  pressure  of  steam  on  the  piston  of  an  engine  is  30  Ib.  per  square 
inch.    If  the  diameter  of  the  piston  is  18  in.,  its  stroke  2  ft.,  how  much 
work  does  the  engine  do  per  hour  if  its  speed  is  110  r.p.m.? 

3.  Calculate  the  horsepower  of  the  engine  in  the  above  problem. 

4.  Why  will  two  horses  be  able  to  draw  a  heavy  load  up  a  hill  when  a 
40-hp.  automobile  will  be  unable  to  do  so?    Explain  the  reason  in  detail. 

6.  Calculate  the  horsepower  of  a  traction  engine  required  to  draw  a  plow 
at  the  rate  of  2  miles  per  hour  if  the  pull  on  the  drawbar  is  15,000  Ib. 

6.  Convert  the  following  readings  in  degrees  Centigrade  to  the  Fahren- 
heit scale: 

-  18,  -  2,  15,  53,  78. 


PRINCIPLES  AND  DEFINITIONS  15 

7.  Convert  the  following  readings  of  the   Fahrenheit  scale  to  degrees 
Centigrade : 

-  20,  10,  60,  80,  220,  350. 

8.  A  pound  of  gasoline  will  yield,  when  completely  burned,  19,200  heat 
units;  calculate  the  foot-pounds  of  energy  contained. 

9.  Calculate  the  heat  required  to  raise  the  temperature  of  1  Ib.  of  cast 
iron,  of  copper,  of  glass,  of  stone  and  of  water  through  100°F.    *.    . 

10.  Calculate  and  compare  the  weights  of  a  gallon  of  kerosene,  of  gasoline, 
of  ethyl  alcohol,  of  ammonia  and  of  water. 

11.  Calculate  the  indicated  horsepower  of  an  engine  having  the  following 
dimensions: 

Diameter  of  cylinder 16  in. 

Diameter  of  piston  rod 2^  in. 

Stroke 24  in. 

Revolutions  per  minute 120 

Mean  effective  pressure,  head  end 52.3 

Mean  effective  pressure,  crank  end 52.0 

12.  A  gasoline  engine  running  at  300  r.p.m.  is  tested  by  means  of  a 
Prony  brake.     If  the  length  of  the  brake  arm  is  42  in.  and  the  net  weight 
as  registered  on  the  platform  scales  is  35  Ib.,  calculate  the  brake  horsepower 
developed  by  the  engine. 


CHAPTER  III 
STEAM  GENERATION  AND  STEAM  BOILERS 

Theory  of  Steam  Generation. — If  heat  is  added  to  ice,  the 
effect  will  be  to  raise  its  temperature  until  the  thermometer 
indicates  32°F.  When  this  point  is  reached,  a  further  addition 
of  heat  does  not  produce  an  increase  in  temperature  until  all  the 
ice  is  changed  into  water,  or  in  other  words  the  ice  melts.  It  has 
been  found  experimentally  that  144  B.t.u.  are  required  to  change 
1  Ib.  of  ice  into  water.  This  quantity  is  called  the  latent  heat 
of  liquefaction  of  ice. 

After  the  quantity  of  ice  given,  which  for  simplicity  may  be 
taken  as  1  Ib.,  has  all  been  turned  into  water,  it  will  be  found  that 
if  more  heat  is  added  the  temperature  of  the  water  will  again 
increase,  though  not  as  rapidly  as  did  that  of  the  ice.  While 
the  addition  of  each  British  thermal  unit  increases  the  tempera- 
ture of  ice  2°F.,  in  the  case  of  water  an  increase  of  only  about  1° 
will  be  noticed  for  each  British  thermal  unit  of  heat  added. 
This  difference  is  due  to  the  fact  that  the  specific  heat,  or  resist- 
ance offered  by  ice  to  a  change  in  temperature  is  one-half  that 
offered  by  water.  That  is,  the  specific  heat  of  ice  is  0.5. 

If  the  water  is  heated  in  a  vessel  open  to  the  atmosphere,  its 
temperature  will  keep  on  going  up  until  about  212°F.,  the  boiling- 
point  of  water,  when  further  addition  of  heat  will  not  produce 
any  temperature  changes,  but  steam  will  issue  from  the  vessel. 
It  has  been  found  that  about  970  B.t.u.  will  be  required  to  change 
1  Ib.  of  water  at  atmospheric  pressure  and  at  212°F.  into  steam. 
The  quantity  of  heat  so  supplied  which  changes  the  physical 
state  of  water  from  the  liquid  state  to  steam  is  called  the  latent 
heat  of  vaporization.  . 

If  the  above  operations  are  performed  in  a  closed  vessel,  water 
will  boil  at  a  higher  temperature  than  212°F.,  since  the  steam 
driven  off  cannot  escape  and  is  compressed,  raising  the  pressure 
and  consequently  the  temperature.  The  latter  is  the  condition 
in  an  ordinary  steam  boiler. 

16 


STEAM  GENERATION  AND  STEAM  BOILERS     17 

That  the  boiling-point  of  water  depends  on  the  pressure  is 
well  known.  Thus  in  a  place  in  Colorado  where  the  altitude  is 
6,000  ft.  above  sea  level  and  the  barometric  pressure  is  12.6  Ib. 
per  square  inch  the  boiling-point  of  water  is  about  204°F.  as 
compared  with  212°F.  at  sea  level  where  the  barometric  pressure 
is  14.7  Ib.  per  square  inch. 

As  the  pressure  is  increased  to  60  Ib.  per  square  inch  by  the 
gage,  it  will  be  found  that  the  boiling-point  of  water  is  275°F. 
At  100  Ib.  per  square  inch  water  will  boil  at  317°F,  and  at  150  Ib. 
the  temperature  will  read  350.5°F.  before  steam  will  be  formed. 

Steam  is  spoken  of  as  being  in  three  conditions : 

1.  Wet. 

2.  Dry. 

3.  Superheated. 

In  the  first  case  the  steam  carries  with  it  a  certain  amount  of 
water  which  has  not  been  evaporated.  The  percentage  of  this 
water  determines  the  condition  of  the  steam;  that  is,  if  there  is 
3  per  cent.,  by  weight,  of  moisture,  the  steam  is  spoken  of  as  being 
97  per  cent.  dry.  A  stationary  boiler,  properly  erected  and  oper- 
ated and  of  suitable  size,  should  generate  steam  that  is  98  per 
cent.  dry.  If  there  is  more  than  3  per  cent,  moisture,  there  is 
every  reason  to  believe  that  the  boiler  is  improperly  installed, 
inefficiently  operated,  or  is  too  small  for  the  work  to  be  done. 

In  the  second  condition,  that  of  dry  steam,  the  vapor  carries 
with  it  no  water  that  has  not  been  evaporated;  that  is,  it  is  dry. 
Any  loss  of  heat,  however  small,  not  accompanied  by  a  correspond- 
ing reduction  in  pressure,  will  cause  condensation,  and  wet  steam 
will  be  the  result.  Steam,  whether  wet  or  dry,  has  a  definite 
temperature  corresponding  to  its  pressure. 

An  increase  in  temperature  not  accompanied  by  an  increase  in 
pressure  will  cause  the  steam  to  acquire  a  condition  that  will 
permit  a  loss  of  heat  at  constant  pressure  without  condensation 
necessarily  following.  This  third  condition  is  called  superheat. 
The  advantage  of  superheated  steam  lies  in  the  fact  that  its 
temperature  may  be  reduced  by  the  amount  of  the  superheat 
without  causing  condensation.  This  makes  it  possible  to  trans- 
mit the  steam  through  mains  and  still  have  it  dry  and  saturated 
at  the  time  it  reaches  the  engine  cylinder.  Superheated  steam 
may  be  secured  by  passing  saturated  steam  through  coils  of  pipe 


18 


FARM  MOTORS 


in  the  path  of  the  hot  flue  gases  from  the  boiler  to  the  chimney. 
An  apparatus  for  superheating  steam  is  called  a  superheater. 

The  pressure  of  steam  will  remain  constant  if  it  is  used  as  fast 
as  it  is  generated.  If  an  engine  uses  steam  too  rapidly  the  boiler 
pressure  will  drop  and  similarly  if  the  fuel  is  burned  at  a  constant 
rate  and  an  insufficient  amount  of  steam  is  used  the  pressure  of 
the  steam  in  the  boiler  will  increase. 

In  Table  3  are  given  some  of  the  most  important  properties  of 
saturated  steam,  which  include: 

1.  Pressure  of  steam  in  pounds  per  square  inch  absolute. 

TABLE  3. — PROPERTIES  OF  SATURATED  STEAM 
English  Units 


Abs.   pres- 
sure, 
pounds 
per  sq.  in. 

Vaporiza- 
tion tem- 
perature, 
degrees  F. 

Heat 
of  the 
liquid 

Latent 
heat 
of  evapo- 
ration 

Total 
heat 
of  steam 

Specific 
volume, 
cubic   feet 
per  Ib. 

Density, 
pounds 
per  cu.  ft. 

Abs. 
pres- 
sure, 
pounds 
per 
sq.  in. 

1 

101.8 

69.8 

1,034.6 

1,104.4 

333.00 

0.00300 

1 

2 

126.1 

94.1 

1,021.4 

1,115.5 

173.30 

0.00577 

2 

3 

141.5 

109.5 

1,012.3 

1,121.8 

118.50 

0.00845 

3 

4 

153.0 

120.9 

1,005.6 

1,126.5 

90.50 

0.01106 

4 

5 

162.3 

130.2 

1,000.2 

1,130.4 

73.33 

0.01364 

5 

6 

170.1 

138.0 

995.7 

1,133.7 

61.89 

0.01616 

6 

7 

176.8 

144.8 

991.6 

1,136.4 

53.58 

0.01867 

7 

8 

182.9 

150.8 

988.0 

1,138.8 

47.27 

0.02115 

8 

9 

188.3 

156.3 

984.8 

1,141.1 

42.36 

0.02361 

9 

10 

193.2 

161.2 

981.7 

1,142.9 

38.38 

0.02606 

10 

14.7 

212.0 

180.1 

970.0 

1,150.1 

26.79 

0.03733 

14.7 

20 

228.0 

196.2 

959.7 

1,155  .'9 

20.08 

0.04980 

20 

30 

250.3 

218.9 

944.8 

1,163.7 

13.74 

0.07280 

30 

40 

267.3 

236.2 

933.0 

1,169.2 

10.49 

0.09530 

40 

50 

281.0 

250.2 

923.2 

1,173.4 

8.51  . 

0.11750 

50 

60 

292.7 

262.2 

914.6 

1,176.8 

7.17 

0.13940 

60 

70 

302.9 

272.7 

906.9 

1,179.6 

6.20 

0.16120 

70 

80 

312.0 

282.1 

900.1 

J,182.2 

5.47 

0.18290 

80 

90 

320.3 

290.6 

893.7 

1,184.3 

4.89 

0.20450 

90 

100 

327.8 

298.4 

887.8 

1,186.2 

4.430 

0.22570 

100 

125 

344.4 

315.5 

874.6 

1,190.1 

3.582 

0.27920 

125 

150 

358.5 

330.1 

863.1 

1,193.2 

3.013 

0.33190 

150 

200 

381.9 

354.6 

843.3 

1,197.9 

2.289 

0.43700 

200 

250 

401.1 

374.7 

826.6 

1,201.3 

1.848 

0.54100 

250 

300 

417.5 

392.0 

811.8 

1,203.8 

1.547 

0.64700 

300 

STEAM  GENERATION  AND  STEAM  BOILERS     19 

2.  Temperatures  of  steam  in  degrees  Fahrenheit.     This  column 
of  temperatures  shows  the  vaporization  temperature  at  each  of 
the  given  pressures. 

3.  Heat  of  the  liquid,  or  the  heat  required  to  bring  up  a 
pound  of  water  from  freezing-point  to  boiling-point. 

4.  The  latent  heat,  or  the  heat  required  to  vaporize  a  pound 
of  water  at  the  given  pressure  after  boiling-point  is  reached. 

5.  The  volume  of  1  Ib.  of  steam  at  the  various  pressures. 

6.  Density  of  steam  in  pounds  per  cubic  foot. 

Fuels. — The  fuels  most  commonly  used  for  steam  generation 
are  coal,  wood,  petroleum  oils  and  natural  gas.  The  combus- 
tible, or  heat-producing,  constituents  of  all  fuels  are  carbon  and 
hydrogen.  A  fuel  containing  much  sulphur  should  be  avoided 
for  steam  generation  on  account  of  the  injurious  sulphurous  acid 
formed  when  the  fuel  is  burned. 

Wood  is  but  little  used  for  steam  generation  except  in  remote 
places,  where  timber  is  plentiful  or  in  special  cases  where  sawdust, 
shavings  and  pieces  of  wood  are  by-products  of  manufacturing 
operations.  Wood  burns  rapidly  and  with  a  bright  flame,  but 
does  not  evolve  much  heat.  When  first  cut,  wood  contains  30  to 
50  per  cent,  of  moisture,  which  can  be  reduced  by  drying  to  about 
15  per  cent.  One  pound  of  dry  wood  is  equal  in  heat-producing 
value  to  % o  Ib.  of  s°ft  coal.  It  is  important  that  wood  be  dry, 
as  each  10  per  cent,  of  moisture  reduces  its  heat-producing  value 
as  a  fuel  by  about  12  per  cent. 

Coal  is  more  extensively  used  as  a  fuel  for  steam  generation 
than  any  other  substance.  All  coals  are  derived  from  vegetable 
origin  and  are  classified  as  follows: 

1.  Anthracite,    or    hard    coal,    consisting  mainly   of    carbon. 
This  coal  is  slow  to  ignite,  burns  with  very  little  flame,  produces 
and  gives  off  very  little  smoke.     Anthracite  coal  contains  very 
little  volatile  matter  and  may  contain  none. 

2.  Semianthracite  coal  is  softer  and  lighter  than  anthracite, 
and  contains  less  carbon  and  from  7  to  12  per  cent,  volatile  matter. 

3.  Semibituminous,  which  contains  from  12  to  25  per  cent, 
volatile  matter  and  less  fixed  carbon  than  the  semianthracite. 

4.  Bituminous,  or  soft,  coal  contains  more  than  20  per  cent, 
of  volatile  matter  and  only  about  50  per  cent,  of  fixed  carbon. 

5.  Lignite,  which  may  be  classified  as  soft  coal  arrested  in  the 


20  FARM  MOTORS 

process  of  formation.  This  coal  contains  a  very  large  proportion 
of  volatile  matter  and  less  than  50  per  cent,  fixed  carbon.  How- 
ever, it  has  a  good  heating  value  and  is  usually  a  free  burner, 
but  owing  to  the  high  percentage  of  volatile  matter  it  will  not 
stand  storage,  but  crumbles  badly  soon  after  exposure  to  air. 

Other  solid  fuels  used  to  some  extent  for  steam  generation  are : 
Peat,  which  is  an  intermediate  between  wood  and  coal  and  found 
in  bogs;  sawdust,  oak  bark  after  it  has  been  used  in  the  process 
of  tanning,  bagasse  or  the  refuse  of  cane  sugar,  and  cotton 
stalks.  Coke  is  also  used  to  some  extent,  the  advantage  of  this 
fuel  as  compared  with  coal  being  that  coke  will  not  ignite  spon- 
taneously, will  not  deteriorate  or  decompose  when  exposed  to 
the  atmosphere,  and  produces  no  smoke  when  burned.  Coke  is 
manufactured  by  burning  coal  in  a  limited  air  supply,  the  volatile 
hydrocarbons  being  driven  off  during  the  process. 

Petroleum  fuels,  either  in  the  form  of  crude  petroleum  or  as 
the  refuse  left  from  its  distillation,  are  used  for  making  steam  to 
a  considerable  extent  in  certain  parts  where  the  relative  cost  of 
oil  is  less  than  that  of  coal.  It  has  been  estimated  that  petro- 
leum oils  at  2  cts.  per  gallon  are  equally  economical  for  steam 
making  as  coal  at  $3  per  ton.  The  advantages  of  oil  as  com- 
pared with  solid  fuels  are  ease  of  handling,  cleanliness  and 
absence  of  smoke  after  combustion. 

Natural  gas  is  used  for  steam  generation  where  its  cost  is  low. 
If  the  cost  of  natural  gas  is  greater  than  10  cts.  per  1,000  cu.  ft. 
it  cannot  compete  with  coal  at  $3  a  ton.  Illuminating  gas  is  too 
expensive  for  steam  generation  and  cannot  compete  with  other 
fuels. 

Combustion. — Combustion  is  a  chemical  combination  of  the 
heat-producing  constituents  of  a  fuel  with  oxygen  and  is  accom- 
panied by  the  production  of  heat  and  light.  The  supply  of  oxy- 
gen for  combustion  is  taken  from  the  atmosphere,  every  pound 
of  air  consisting  of  0.23  part  by  weight  of  oxygen  and  0.77  part 
by  weight  of  nitrogen. 

It  has  been  found  that  most  coals  require  between  11  and  12 
Ib.  of  air  for  every  pound  of  coal  burned  and  that  the  heat  de- 
veloped during  the  combustion  of  1  Ib.  of  the  various  fuels  is  as 
follows: 


STEAM  GENERATION  AND  STEAM  BOILERS     21 
TABLE  4. — HEAT  DEVELOPED  BY  THE  COMBUSTION  OP  VARIOUS  FUELS 


Name  of  fuel 

Heat  developed  in  B.t.u. 
per  pound  of  fuel 

Heat  developed  in  B.t.u. 
per  cubic  foot  of  fuel 

Anthracite  coal 

13  200  to  13  900 

Semibituminous  coal  

13,000  to  16  000 

Bituminous  coal  

12  000  to  15  000 

Lignite  .     ... 

8  500  to  11  400 

Peat  (dry)  .  . 

8,000  to  11,000 

Wood     

8,200  to    9  200 

Petroleum  fuels  . 

18  000  to  20  000 

. 

Kerosene  •.  .  . 

18,550 

Gasoline 

19,000 

Alcohol  (100  per  cent  ) 

11  500 

Natural  gas  

900  to  1,000 

Illuminating  gas 

600  to     700 

Producer  gas 

100  to     150 

Commercial  Value  of  Fuels. — In  the  furnace  of  the  actual 
boiler  plant  only  30  to  70  per  cent,  of  the  heat  units  contained 
in  the  given  fuel  is  utilized  for  the  generation  of  steam.  The 
principal  losses  in  the  boiler  furnace  are  due  to  incomplete  com- 
bustion, infiltration  of  air  through  setting,  and  to  the  heat  carried 
away  in  the  flue  gases.  The  methods  to  be  employed  in  order  to 
reduce  these  losses  to  a  minimum  will  be  discussed  under  boiler 
management. 


STEAM  BOILERS  AND  AUXILIARIES 

.Principal  Parts  of  a  Steam  Power  Plant. — The  principal  parts 
of  a  steam  power  plant  are  illustrated  in  Fig.  3,  and  include  the 
following : 

A  furnace  in  which  the  fuel  is  burned.  This  consists  of  a 
chamber  arranged  with  a  grate  (1),  if  coal  or  any  other  solid  fuel 
is  used,  and  with  burners  when  the  fuel  is  in  the  liquid  or  gaseous 
state.  The  furnace  is  connected  through  a  flue  or  breeching  (2) 
to  a  chimney.  The  function  of  a  chimney  is  to  produce  suffi- 
cient draft,  so  that  the  fuel  will  have  the  proper  amount  of  air 
for  combustion;  it  also  serves  to  carry  off  the  obnoxious  gases 
after  the  combustion  process  is  completed.  The  flue  leading  to 


22 


FARM  MOTORS 


the  chimney  is  provided  with  a  damper  (3),  so  that  the  intensity 
of  the  draft  can  be  regulated. 

A  boiler  (4),  which  is  a  closed  metallic  vessel  filled  to  about  two- 
thirds  of  its  volume  with  water.  The  heat  developed  by  burning 
the  fuel  in  the  furnace  is  utilized  in  converting  the  water  con- 
tained in  the  boiler  into  steam.  The  boiler  (4)  is  arranged  with 
a  water  column (5)  to  show  the  water  level,  with  a  safety  valve (6) 
to  prevent  the  pressure  from  rising  too  high,  and  with  a  gage (7) 
to  indicate  the  steam  pressure. 


FIG.  3. — Steam,  power  plant. 

The  function  of  a  setting  is  to  provide  correct  spaces  for  the 
furnace,  combustion  chamber  and  ashpit,  to  support  the  boiler 
shell,  to  prevent  air  from  entering  the  furnace  above  the  fuel 
bed,  and  to  decrease  the  heat  radiation  to  a  minimum. 

The  feed  pump  (8)  supplies  the  boiler  with  water  through  the 
feed  pipe  (9). 

The  steam  lines  (10)  and  (11)  convey  steam  from  the  boiler  to 
the  engine  and  to  the  steam  end  of  the  pump  respectively. 


STEAM  GENERATION  AND  STEAM  BOILERS     23 

In  the  engine  the  energy  of  the  steam  is  expended  in  doing 
work.  The  steam  enters  the  engine  cylinder  (12)  through  the  valve 
(13)  and  pushes  on  the  piston  (14).  The  sliding  motion  of  the  pis- 
ton, which  is  transmitted  to  the  piston  rod  (15),  is  changed  into 
rotary  motion  at  the  shaft  (16)  by  means  of  a  connecting  rod  (17) 
and  crank  (18). 

The  exhaust  pipe  (19)  conveys  the  used  steam  to  the  atmo- 
sphere, to  the  condenser,  or  to  some  use  where  its  heat  is  ab- 
stracted, converting  the  steam  back  into  water. 

Classification  of  Boilers. — Boilers  are  divided  into  fire-tube 
and  water-tube  types.  In  the  fire-tube  the  hot  gases  developed 
by  the  combustion  of  the  fuel  pass  through  the  tubes,  while 
in  the  water-tube  boilers  these  gases  pass  around  the  tubes. 
Either  type  may  be  constructed  as  a  vertical  or  as  a  horizontal 
boiler,  depending  on  whether  the  axis  of  the  shell  is  vertical  or 
horizontal. 

The  fire-tube  boiler  may  be  externally  or  internally  fired. 
In  the  externally  fired  boiler  the  furnace  is  in  the  brick  setting 
entirely  outside  of  the  boiler  shell,  while  in  the  internally  fired 
types  the  furnace  is  in  the  boiler  shell,  no  brick  setting  being 
necessary.  For  stationary  work  the  externally  fired  boiler  is 
most  common,  while  the  internally  fired  types  are  always  used 
for  locomotive  and  traction  engine  purposes  and  generally  for 
marine  use.  Vertical  fire-tube  boilers  are  usually  internally 
fired. 

Return  Tubular  Boiler. — Boilers  of  this  type  are  most  com- 
monly used  in  this  country.  The  general  appearance  of  a  re- 
turn tubular  boiler  is  shown  in  Fig.  4.  Fig  5  illustrates  the  de- 
tails of  the  setting.  The  height  of  the  boiler  above  the  grate 
depends  upon  the  fuel  employed. 

These  boilers  as  seen  from  the  cuts  consist  of  a  cylindrical 
shell  closed  at  the  end  by  two  flat  heads,  and  of  numerous  small 
tubes  which  extend  the  whole  length  of  the  shell.  Two-thirds 
of  the  volume  of  the  shell  is  filled  with  water,  the  remaining  part 
being  left  for  the  disengagement  of  the  steam  from  the  water, 
and  called  the  steam  space.  Sometimes,  as  shown  in  Fig.  6,  a 
steam  dome  D  is  provided  to  increase  the  volume  of  the  steam 
space.  The  coal  burns  upon  the  grates  which,  as  shown  in  Fig. 
5,  rest  upon  the  bridge-wall  W  and  upon  the  front  of  the  setting. 


24 


FARM  MOTORS 


sssSIS^^  !/^!\v»w  o  •  •  r  »*^»*  •  %' 


pIQt  4. — Return  tubular  boiler. 


FIG.  5.— Details  of  boiler  setting. 


FIG.  0. — Boiler  with  dome. 


STEAM  GENERATION  AND  STEAM  BOILERS     25 


The  gases  pass  from  the  furnace  under  and  along  the  boiler  shell 
to  the  back  connection  or  combustion  chamber  C,  and  from 
there  to  the  front  through  the  tubes  and  up  the  uptake  to  the 
breeching  or  flue  which  leads  to  the  chimney. 

Vertical  Fire-tube  Boilers. — Two  forms  of  vertical  boilers  are 
shown  in  Figs.  7  and  8.     In  the  form  shown  in  Fig.  7  the  tops 


FIG.  7. — Vertical  boiler. 
Exposed  tube  type. 


FIG.  8. — Vertical  boiler. 

Submerged  tube  type. 


of  the  tubes  are  above  the  water  line  and  may  become  overheated 
when  the  boiler  is  forced.  To  prevent  injury  from  this  cause, 
some  forms  of  vertical  boilers  are  constructed  as  shown  in  Fig.  8, 
the  tops  of  the  tubes  being  ended  in  a  submerged  tube-sheet 
which  is  kept  below  the  water  line. 
The  essential  parts  of  all  forms  of  vertical  boilers  are  a  cylin- 


26  FARM  MOTORS 

drical  shell  with  a  firebox  and  ashpit  in  the  lower  end.  The 
tubes  lead  directly  from  the  furnace  to  the  upper  head  of  the 
shell.  The  hot  gases  from  the  furnace  pass  through  the  tubes 
and  out  of  the  stack. 

Vertical  boilers  occupy  little  floor  space  and  require  no  setting 
or  foundation.  They  can  also  be  used  as  portable  boilers. 

Water-tube  Boilers. — Water-tube  boilers  are  used  in  large 
power  plants  on  account  of  their  adaptability  to  higher  pressures 
and  larger  sizes,  decreased  danger  from  serious  explosions, 
greater  space  economy,  and  rapidity  of  steam  generation.  For 
small  power  plants  the  fire-tube  boiler  is  usually  more  suitable 
on  account  of  its  lower  first  cost.  Also  in  a  fire-tube  boiler  if  a 
tube  should  break,  the  boiler  can  be  repaired  by  plugging  without 
interrupting  service,  which  is  not  the  case  with  most  types  of 
water-tube  boilers.  As  far  as  economy  is  concerned,  numerous 
tests  show  that  either  type  when  properly  designed  and  operated 
will  give  the  same  economy. 

There  are  many  different  types  of  water-tube  boilers  on  the 
market,  but  the  essential  parts  of  all  are  tubes  filled  with  water 
and  one  or  more  drums  for  the  disengagement  of  the  steam  from 
the  water. 


(b) 
FIG.  9. — Grate  bars. 

Grates  for  Boiler  Furnaces. — Grates  are  formed  of  cast-iron 
bars.  Several  forms  of  grate  bars  are  illustrated  in  Figs.  9  and 
10.  Plain  grates  (&),  Fig.  9,  are  best  adapted  for  caking  coals 
and  are  usually  provided  with  iron  bars  cast  in  pairs  and  lugs 
at  the  side.  The  Tupper  type  of  grate  (c),  Fig.  9,  is  more  suitable 
for  the  burning  of  hard  coal,  which  does  not  cake.  The  grates 
of  a  boiler  furnace  can  be  easily  interchanged  to  suit  the  fuel 
burned.  For  most  economical  results  some  form  of  rocking  and 
dumping  grate,  as  shown  in  Fig.  10,  should  be  used. 

Piping  for  Boilers. — Pipes  used  for  carrying  steam  are  made  of 
wrought  iron  or  of  steel.  Wrought-iron  pipe  is  superior  to  steel 


STEAM  GENERATION  AND  STEAM  BOILERS     27 

pipe  as  far  as  durability  is  concerned,  but  is  more  expensive  and 
more  difficult  to  secure.  Sizes  of  pipe  are  named  by  the 
inside  diameter,  while  boiler  tubes  go  by  the  outside  diameter. 
Standard  steam  pipe  is  made  in  sizes  of  J£,  Ji  M>  M>  /4>  1> 
1J4  1M,  2,  2M,  3,  3M,  4,  4M,  5,  6,  7,  8,  9,  10,  11  and  12  in. 
Sizes  above  12  in.  are  named  by  the  outside  diameter. 

The  various  grades  of  pipe  are  merchant,   standard,   extra 
heavy  and  double  extra  heavy.     Merchant  pipe  is  somewhat 


FIG.  10. — Dumping  grate. 


lighter  than  standard  pipe  and  its  manufacture  is  being  discon- 
tinued. Extra  heavy  and  double  extra  heavy  have  the  same  out- 
side diameters  as  standard  pipe,  but  the  inside  diameters  are 
smaller,  due  to  the  greater  thickness  of  the  pipe. 

Steam  pipe  lines  should  always  be  laid  with  a  gradual  inclina- 
tion downward,  so  as  to  allow  the  condensation  that  occurs  to 
flow  in  the  direction  in  which  the  steam  is  moving.  If  this  is 
not  done  water  may  accumulate,  will  be  picked  up  by  the  steam 
and  may  cause  much  damage  by  water-hammer. 

Pipe  Fittings. — Fig.  11  illustrates  several  forms  of  pipe  unions, 
which  are  used  for  uniting  two  lengths  of  pipe. 

The  elbow  or  ell  shown  in  Fig.  12  is  employed  for  connecting 
two  pipes  of  the  same  size  and  at  an  angle  to  each  other.  If 
the  pipes  are  of  different  diameters  a  reducing  ell  as  shown  in 
Fig.  13  should  be  used. 

The  tee  shown  in  Fig.  14  is  used  for  making  a  branch  at  right 
angles  to  a  pipe  line. 

The  cross  shown  in  Fig.  15  is  used  when  two  branches  must  be 
made  in  opposite  directions. 

In  order  to  reduce  the  size  of  a  pipe  line  a  bushing,  Fig.  16,  or 
a  reducer,  Fig.  17,  can  be  used. 

To  close  the  end  of  a  pipe  a  cap,  Fig.  18,  is  used,  while  the  plug 


28 


FARM  MOTORS 


shown  in  Fig.  19  is  used  to  close  a  pipe  threaded  on  the  inside  or 
to  close  a  fitting. 


FIG.  11. — Pipe  unions. 


Fia.  13.— Reducing  Ell. 


FIG.  14.— Tees. 


Fia.  15.— Cross.        FIG.  16.— Bushing.    FIG.  17.— Reducer. 


FIG.  18.— Cap.      FIG.  19.— Plug- 

Valves. — The  function  of  a  valve  is  to  control  and  regulate  the 
flow  of  water,  steam,  or  gas  in  a  pipe.     In  the  globe  valve  in  Fig. 


STEAM  GENERATION  AND  STEAM  BOILERS     29 

20  the  fluid  usually  enters  at  the  right,  passes  under  the  valve  and 
out  at  the  left. 

This  method  of  installation  places  the  pressure  of  the  steam,  or 
other  fluid,  against  the  disc  in  such  a  way  that  it  tends  to  open  the 
valve.  The  advantages  claimed  for  this  method  are: 


FIG.  20.— Globe  valve.         FIG.  21.— Gate  valve.      FIG.  22.— Angle  valve 

1.  When  the  valve  is  closed  the  stem  may  be  packed  without 
cutting  the  steam  pressure  off  the  entire  line. 

2.  The  adjustment  of  the  opening  can  be  made  more  accu- 
rately against  the  steam  pressure  than  with  it. 

3.  The  flow  of  steam 
tends  to  keep  the  valve 
seat  free  from  scale  and 
other  dirt. 

Those  who  favor  the 
other  method  claim,  as 
the  principal  advantage, 
that  the  pressure  of  the 
steam,  when  the  valve  is  closed,  tends  to  keep  it  in  that  position 
and  that  there  is  much  less  likelihood  of  the  valve  leaking.  Both 
methods  will  be  found  in  use,  but  it  is  probable  that  a  large 
majority  of  the  installations  will  be  found  to  be  in  accordance 
with  the  first  method. 

A  gate  valve  is  shown  in  Fig.  21.     This  form  of  valve  gives  a 


FIG.  23.— Check  valve. 


30 


FARM  MOTORS 


straight  passage  through  the  valve,  and  is  preferable  for  most 
purposes  to  the  globe  valve. 

Fig.  22  illustrates  an  angle  valve  which  takes  the  place  of 
an  ordinary  valve  and  ell. 

The  function  of  a  check  valve  illustrated  in  Fig.  23  is  to  allow 
water  or  steam  to  pass  in  one  direction  but  not  in  the  other. 

A  boiler  feed  line  should  always  be  provided  with  a  check  valve 
and  also  with  some  form  of  globe  or  gate  valve  to  enable  the 
operator  to  examine  and  repair  the  check  valve. 

Safety  Valves. — The  function  of  a  safety  valve  is  to  prevent 
the  steam  pressure  from  rising  to  a  dangerous  point.  The  two 


FIG.  24. — Lever  safety  valve. 


PIG.  25. — Pop  safety  valve. 


common  forms  of  safety  valves  are  the  lever  safety  valve  and  the 
spring  or  pop  safety  valve. 

The  lever  safety  valve  shown  in  Fig.  24  consists  of  a  valve  disc 
which  is  held  down  on  the  valve  seat  by  means  of  a  weight  acting 
through  a  lever,  the  steam  pressing  against  the  bottom  of  the 
disc.  The  lever  is  pivoted  at  one  end  to  the  valve  casing  and  is 
marked  at  a  number  of  points  with  the  pressure  at  which  the 
boiler  will  blow  off  if  the  weight  is  placed  at  that  particular  point. 

The  pop  safety  valve  shown  in  Fig.  25  differs  from  the  lever 
valve  in  that  the  valve  disc  is  held  on  its  seat  and  the  steam  pres- 
sure is  resisted  by  a  spring  in  place  of  a  weight  and  lever.  Pop 
safety  valves  can  be  adjusted  to  blow  off  at  various  pressures  by 
tightening  or  loosening  the  spring  pressure  on  the  valve  disc. 


STEAM  GENERATION  AND  STEAM  BOILERS     31 


Steam  Gages. — A  steam  gage  indicates  the  pressure  of  the 
steam  in  a  boiler.  The  most  common  form,  shown  in  Fig.  26, 
consists  of  a  curved  spring  tube  closed  at  one  end  and  filled 


FIG.  26. — Steam  gages. 

with  some  liquid.     One  end  of  the  tube  is  free,  while  the  other  is 

fastened  to  the  fitting  which  is  secured  into  the  space  where 

the  pressure  is  to  be  measured.     Pressure  applied  to  the  inside 

of  the    tube   causes   the  free  end   to 

move.     This  motion  is  communicated 

by  means  of   levers   and   small   gears 

to    the    needle    which  moves   over   a 

graduated  dial  face,    and   records  the 

pressure  directly  in  pounds  per  square 

inch. 

Water  Glass  and  Gage  Cocks. — The 
height  of  the  water  level  in  a  boiler  is 
indicated  by  a  water  glass,  one  end  of 
which  is  connected  to  the  steam  space 
and  the  other  end  to  the  water  space  in 
the  boiler.  All  boilers  should  also  be 
provided  with  three  gage  cocks,  one  of 
which  is  set  at  the  desired  water  level, 
one  above  it  and  one  below.  These 
are  more  reliable  than  the  water  glass 
and  should  be  used  for  checking  the 
glass. 

Water  Column. — The  steam  gage,  water  glass  and 'gage  cocks 
are  usually  fastened  to  a  casting  called  a  water  column.  One 
form  of  water  column  is  shown  in  Fig.  27,  this  also  being  fitted 


FIG.  27. — Water  column. 


32 


FARM  MOTORS 


ByFbss 


with  a  float  and  whistle  to  notify  the  operator  should  the  water 
in  the  boiler  become  too  low  or  too  high.  A  fireman  who  takes 
proper  care  of  the  boilers  in  his  charge  will  never  allow  the  water 
to  be  at  a  height  that  will  necessitate  audible  warning. 

Steam  Traps. — The  object  of  a  steam  trap  is  to  drain  the  water 
from  pipe  lines  without  allowing  the  steam  to  escape.  One  form 

of  steam  trap  is 
shown  in  Fig.  28,  the 
valve  being  controlled 
by  a  float  when  the 
water  in  the  trap  rises 
to  a  sufficient  height. 
Feed  Pumps  and 
Injectors. — Water  is 
forced  into  steam 
boilers  by  pumps  or 
injectors.  A  pump 

,.,      00  will  handle  water  at 

FIG.  28. — Steam  trap. 

any  temperature, 

while  an  injector  can  be  used  only  when  the  water  is  cold. 
The  injector  is  not  as  wasteful  of  steam  as  a  pump  and  for 
feeding  cold  water  to  a  boiler  has  the  additional  advantage, 
that  it  heats  the  water  while  feeding  it  to  the  boiler. 

Feed  pumps  may  be  driven  from  the  crosshead  of  an  engine, 
as  is  often  the  case  on  traction  engines.  Such  pumps  are  very 
simple,  but  can  only  supply  water  to  the  boiler  when  the  engine 
is  in  operation. 

Direct-acting  steam  pumps,  driven  by  their  own  steam  cyl- 
inders, are  most  commonly  used  for  feeding  stationary  boilers, 
as  they  can  be  operated  independently  of  the  main  engine  and 
their  speed  can  be  regulated  to  suit  the  feed  water  demand  of 
the  boilers. 

The  details  of  construction  of  two  forms  of  direct-acting  pumps 
are  shown  in  Figs.  29  and  30. 

In  the  pump  shown  in  Fig.  29,  1  is  the  steam  cylinder  and  2 
is  the  water  cylinder.  The  valve  E  is  moved  by  the  vibrating 
arm  F  .and  admits  steam  into  the  cylinder  1.  If  steam  is  ad- 
mitted at  the  left  of  the  piston  A,  the  piston  will  be  moved  to  the 
right,  pushing  the  plunger  B,  driving  the  water  through  the 


STEAM  GENERATION  AND  STEAM  BOILERS     33 


Pluncjer  and  Ring  Pattern 


FIG.  29. — Boiler  feed  pumps. 


34 


FARM  MOTORS 


water  valve  K,  and  into  the  feed  line  at  0.  While  the  plunger 
is  moving  to  the  right,  a  partial  vacuum  is  formed  at  its  left, 
which  opens  the  valve  N  and  draws  the  water  from  the  supply 
at  C.  When  the  plunger  B  reaches  the  extreme  position  to  the 
right,  the  vibrating  arm  F  moves  the  valve  E  to  the  left,  admit- 
ting steam  which  pushes  the  piston  and  plunger  to  the  left,  driv- 
ing the  water  through  the  valve  L  and  taking  a  new  supply 
through  M.  The  function  of  the  air  chamber  P  is  to  secure  a 


FIG.  30. — Boiler  feed  pump. 

steady  flow  of  water  through  the  discharge  0  and  to  prevent 
shock  in  the  piping. 

The  pump  shown  in  Fig.  30  differs  from  the  one  just  described 
in  that  the  steam  valve  G  is  operated  by  the  steam  in  the  steam 
chest  and  not  by  a  vibrating  arm  outside  of  the  cylinder.  The 
piston  C  is  driven  by  steam  admitted  under  the  slide  valve  <7 ,  this 
valve  being  moved  by  a  plunger  F.  This  plunger  F  is  hollow  at 
the  ends  and  the  space  between  it  and  the  head  of  the  steam  chest 
is  filled  with  steam.  Thus  the  plunger  remains  motionless  until 


STEAM  GENERATION  AND  STEAM  BOILERS     35 


the  piston  C  strikes  one  of  the  valves  /,  exhausting  the  steam 
through  the  part  E  at  one  end.  The  water  end  is  similar  to  that 
of  the  pump  in  Fig.  29. 

Injectors  are  used  very  commonly  for  the  feeding  of  portable 
and  of  small  stationary  boilers.  In  larger  plants  injectors  are 
sometimes  used  in  conjunction  with  pumps  as  an  auxiliary 
method  for  feeding  boilers. 

The  general  construction  of  an  injector  is  illustrated  in  Fig  31. 
Steam  from  the  boiler  enters  the  injector  nozzle  at  A,  flows 


Steam 


Water, 


To  Bo  Her 


FIG.  31. — Injector. 


through  the  combining  tube  BC  and  out  to  the  atmosphere 
through  the  check  valve  E  and  overflow  F.  The  steam  in  ex- 
panding through  the  nozzle  A  attains  considerable  velocity,  and 
forms  sufficient  vacuum  to  cause  the  water  to  rise  to  the  injector. 
The  steam  jet  at  a  high  velocity  coming  into  contact  with  the 
water  is  condensed,  gives  up  its  heat  to  the  water  and  imparts  a 
momentum  which  is  great  enough  to  force  the  water  into  the 
boiler  against  a  steam  pressure  equal  to  or  greater  than  that  of 
the  steam  entering  the  injector. 

As  soon  as  a  vacuum  is  established  in  the  injector,  and  the  water 
begins  to  be  delivered  to  the  boiler,  the  check  valve  E  at  the 
overflow  closes.  Should  the  flow  of  feed  water  to  the  boiler  be 
interrupted,  due  to  air  leaking  into  the  injector  or  to  some  other 
cause,  the  overflow  will  open  and  the  steam  will  escape  to  the 
atmosphere. 

The  method  of  connecting  an  injector  to  a  vertical  boiler  is 


36 


FARM  MOTORS 


illustrated  in  Fig.  32.  To  facilitate  the  taking  down  of  an  injector 
for  inspection  and  repairs  it  should  be  connected  up  with  unions. 
Due  to  the  fact  that  the  vacuum  in  an  injector  is  broken  as 
the  temperature  of  the  water  increases,  injectors  can  only  work 
when  the  feed  water  is  150°F.  or  cooler. 


TANK 


FIG.  32. — Method  of  connecting  an  injector. 

Feed-water  Heaters. — If  cold  water  is  fed  to  a  boiler,  the 
temperature  at  the  place  where  the  water  is  discharged  will  be 
different  from  that  in  the  other  parts  of  the  boiler,  and  strains 
due  to  unequal  expansion  and  contraction  will  be  set  up  which 
will  decrease  the  life  of  the  boiler,  besides  impairing  the  tightness 
of  the  setting.  With  hot  feed  water,  strains  due  to  unequal 
expansion  are  prevented.  Also  for  every  10°  increase  in  the 
temperature  of  the  feed  water  a  gain  of  about  1  per  cent,  in  the 
fuel  economy  can  be  expected.  This  also  means  that  the  capac- 
ity of  a  boiler  plant  can  be  increased  by  the  installation  of  some 
•apparatus,  outside  of  the  boiler,  for  the  heating  of  feed  water. 

This  increase  in  capacity  can  usually  be  accomplished  at  much 
less  cost  .than  by  increasing  the  size  of  the  boiler.  Heating  the 
feed  water  outside  of  the  boiler  serves  also  to  purify  the  water 
bef  oareyit  Centers  -the  boiler. 


STEAM  GENERATION  AND  STEAM  BOILERS     37 

Feed  water  can  be  heated  by  live  steam,  by  exhaust  steam, 
or  by  the  waste  chimney  gases. 

The  heating  of  feed  water  by  live  steam  is  not  recommended, 
as  the  advantage  of  this  method  lies  mainly  in  the  amelioration 
of  unequal  expansion. 

Feed- water  heaters  which  utilize  the  heat  of  exhaust  steam 
from  engines  and  pumps  are  most  commonly  used.  Heaters 
may  be  constructed  so  that  the  exhaust  steam  and  water  come 
into  direct  contact  and  the  steam  gives  up  its  heat  by  condensa- 
tion. Such  heaters  are  called  open  feed-water  heaters.  In  this 
form  water  passes  over  trays  upon  which  the  impurities  thrown 
out  of  the  water  by  heating  it  are  deposited,  and  can  be  easily 
removed. 

If  it  is  desired  to  prevent  the  steam  and  water  from  coming 
into  contact  with  each  other,  some  form  of  closed  heater  should 
be  used.  In  the  case  of  closed  heaters  the  steam  on  one  side  of  a 
tube  heats  the  water  on  the  other.  Such  heaters  may  be  con- 
structed so  that  either  the  steam  or  the  water  flows  through  the 
tubes. 

Chimneys  and  Artificial  Draft-producing  Systems.— A  chim- 
ney or  stack  is  used  to  carry  off  the  obnoxious  gases  formed  dur- 
ing the  process  of  combustion  at  such  an  elevation  as  will  render 
them  unobjectionable.  Another  very  important  function  per- 
formed by  a  chimney  is  to  produce  a  draft  which  will  cause  fresh 
air,  carrying  oxygen,  to  pass  through  the  fuel  bed,  producing 
continuous  combustion. 

The  draft  produced  by  a  chimney  is  due  to  the  fact  that  trtie  hot 
gases  inside  the  chimney  are  lighter  than  the  outside  cold  air.  In 
the  boiler  plant  the  cold  air  is  heated  in  passing  through  the  fuel 
bed,  rises  through  the  chimney  and  is  replaced  by  cold  air  entering 
under  the  grate. 

The  amount  of  draft  produced  by  a  chimney  depends  on  its 
height;  the  taller  the  chimney,  the  greater  is  the  draft  produced, 
since  the  difference  in  weight  between  the  column  of  the  air  inside 
and  that  of  the  air  outside  increases  as  the  height  of  the  chimney. 

The  intensity  of  chimney  draft  is  measured  in  inches  of  water, 
which  means  that  the  draft  is  strong  enough  to  support  a  column 
of  water  of  the  height  given.  The  draft  produced  by  chimneys  is 
usually  J^  to  %  in.  of  water. 


38  FARM  MOTORS 

Chimneys  are  made  of  brick,  concrete,  or  steel.  For  small 
plants  steel  stacks  are  more  desirable.  A  brick  chimney  unless 
carefully  constructed  may  allow  large  quantities  of  air  to  leak  in, 
which  will  interfere  with  the  intensity  of  the  draft.  Steel  stacks 
are  also  cheaper.  Brick  chimneys  as  usually  constructed  have 
two  walls,  with  an  air  space  between  them.  The  inside  wall 
should  be  lined  with  firebrick. 

Draft  produced  by  chimneys  is  called  natural  draft. 

In  some  cases  the  draft  produced  by  chimneys  is  insufficient 
and  some  artificial  method  has  to  be  used. 

Artificial  draft  may  be  produced  by  steam  jets,  as  is  common  in 
locomotive  and  traction-engine  practice.  This  system  is  uneco- 
nomical, and  is  used  only  in  connection  with  land  boilers  to 
reduce  the  clinkering  of  certain  grades  of  coal. 

Firing. — To  the  average  person  firing  consists  merely  of  open- 
ing the  furnace  door  and  throwing  fuel  on  the  grate.  It  has  been 
found  that  some  system  of  firing  must  be  adopted  in  order  to 
produce  economical  combustion  of  coal. 

The  method  to  be  adopted  depends  mainly  on  the  kind  of  fuel. 

The  spreading  method  consists  of  distributing  a  small  charge 
of  coal  in  a  thin  layer  over  the  entire  grate.  This  system  will 
give  satisfactory  results  with  anthracite  coal  and  with  some 
bituminous  coals.  With  this  method,  if  the  fuel  is  fed  in  large 
quantities  and  at  long  intervals,  incomplete  combustion  will 
result. 

The  alternate  method  consists  of  covering  first  one  side  of  the 
grate  with  fresh  fuel  and  then  the  other.  The  volatile  gases 
that  pass  off  from  the  fresh  fuel  on  one  side  of  the  grate  are  burned 
with  the  hot  air  coming  from  the  bright  side  of  the  fire.  This 
system  is  best  applied  to  a  boiler  with  a  broad  furnace. 

The  coking  method  is  best  adapted  for  smoky  and  for  the  cak- 
ing varieties  of  bituminous  coal.  In  this  method  the  coal  is  put 
in  the  front  part  of  the  furnace,  and  allowed  to  remain  there  until 
the  volatile  gases  are  driven  off;  it  is  then  pushed  back  and  spread 
over  the  hot  part  of  the  furnace,  and  a  new  charge  is  thrown  in  the 
front. 

Either  one  of  the  three  systems  of  firing  explained  will  produce 
good  results,  if  properly  carried  out  and  if  the  fire  is  kept  bright 
and  clean.  Smoke  indicates  incomplete  combustion  and  with 


STEAM  GENERATION  AND  STEAM  BOILERS     39 

bituminous  coal  occurs  if  the  volatile  gases  are  allowed  to  pass  off 
unburned.  If  the  boiler  is  set  too  close  to  the  grate,  the  volatile 
gases  driven  off  from  the  coal  are  brought  into  contact  with  the 
comparatively  cool  surfaces  of  the  boiler  shell  or  tubes  and  smoke 
is  produced. 

In  all  cases  the  best  results  can  be  obtained  by  firing  coal 
frequently  and  in  small  quantities.  With  mechanical  stokers 
this  can  be  accomplished  and  one  man  can  attend  to  a  large 
number  of  furnaces. 

When  using  mechanical  stokers  inferior  fuels  can  be  burned 
without  smoke,  but  for  small  power  plants  they  are  not  practical 
on  account  of  the  initial  high  cost,  large  repair'  bills  and  cost  of 
power  for  operating  the  stoker  mechanism. 

Rating  of  Boilers. — Boilers  are  usually  rated  in  horsepower. 
The  term  horsepower  in  this  connection  is  only  a  matter  of  con- 
venience in  rating  boilers,  and  does  not  mean  the  rate  of  doing 
work,  but  is  an  arbitrary  unit  applying  to  the  evaporation  of  a 
definite  amount  of  water.  The  American  Society  of  Mechanical 
Engineers  has  recommended  that  one  boiler  horsepower  should 
mean  the  evaporation  of  30  Ib.  of  water  per  hour  at  100°F.  into 
steam  at  70  Ib.  gage.  This  is  equivalent  to  the  evaporation  of 
34J^  Ib.  of  water  from  feed  water  at  212°F.  into  steam  at  212°F.' 

Boiler  manufacturers  often  rate  boilers  in  square  feet  of  heating 
surface.  It  has  been  found  that  each  square  foot  of  boiler  heat- 
ing surface  can  evaporate  economically  3  to  3.4  Ib.  of  water,  so 
that  a  boiler  horsepower  can  be  produced  by  10  to  12  sq.  ft.  of 
boiler  heating  surface. 

Management  of  Boilers. — Before  a  boiler  is  started  for  the 
first  time,  its  interior  should  be  carefully  cleaned,  care  being  taken 
that  no  oily  waste  or  foreign  material  is  left  inside  the  boiler. 
The  various  manholes  and  handholes  are  then  closed  and  the 
boiler  is  filled  to  about  two-thirds  of  its  volume  with  water.  The 
fire  is  started  with  wood,  oily  waste,  or  other  rapidly  burning 
materials,  keeping  the  damper  and  ashpit  door  open.  The  fuel 
bed  is  then  built  up  slowly. 

While  getting  up  the  steam  pressure,  the  water  gage  glass 
should  be  blown  out  to  see  that  it  is  not  choked,  the  gage  cocks 
should  be  tried  and  all  auxiliaries  such  as  pumps,  injectors,  pres- 
sure gages,  piping,  etc.,  carefully  examined.  The  safety  valve 


40  FARM  MOTORS 

should  be  carefully  examined  and  tried  out  before  cutting  the 
boiler  into  service. 

When  cutting  a  boiler  into  service  with  other  boilers,  its  pres- 
sure should  be  the  same  as  that  of  the  other  boilers.  Steam 
valves  should  be  opened  and  closed  very  slowly  in  order  to  pre- 
vent water-hammer  and  stresses  from  rapid  temperature  changes. 

During  the  operation  of  a  steam  boiler  the  safety  valve  should 
be  kept  in  perfect  condition  and  tried  daily  by  allowing  the  pres- 
sure to  rise  gradually  until  the  valve  begins  to  simmer.  Each 
boiler  should  have  its  own  safety  valve  and  under  no  condition 
should  a  stop  valve  be  placed  between  it  and  the  boiler.  The 
steam  gage  should  be  calibrated  from  time  to  time  with  a  stand- 
ard gage  or  still  better  by  means  of  some  form  of  dead-weight 
tester.  It  is  best  not  to  depend  on  the  water  gage  glass  entirely. 
Gage  cocks  are  more  reliable  and  should  be  used  for  checking  the 
water  level  of  a  boiler. 

In  case  of  low  water  do  not  turn  on  the  feed,  but  shut  the 
damper,  cover  the  fuel  bed  with  ashes,  or  if  that  is  not  avail- 
able, with  green  coal.  In  case  of  low  water  the  safety  valve 
should  not  be  lifted  until  the  boiler  has  cooled  down,  or  an  ex- 
plosion may  occur.  Operating  conditions,  as  regards  the  use 
of 'steam,  should  not  be  changed.  If  the  engine  is  running 
allow  it  to  continue,  but  do  not  open  valve  to  reduce  the 
pressure. 

A  boiler  should  be  cleaned  often  and  kept  free  from  scale.  If 
clean  water  is  used  a  boiler  may  be  run  several  months  without 
fear  of  serious  scale  formation,  but  in  most  places  boilers  should  be 
cleaned  at  least  once  each  month.  When  preparing  to  clean  a 
boiler  allow  it  to  cool  down,  and  the  water  to  remain  in  the  shell 
until  ready  to  commence  cleaning. 

In  emergencies  split  tubes  may  be  plugged  with  iron  plugs 
without  throwing  the  boiler  out  of  service.  Also  if  a  tube 
becomes  leaky  in  the  tube-sheet  this  can  be  remedied  by  inserting 
a  tapering  sleeve  slightly  larger  than  the  inside  diameter  of  the 
tube. 

A  boiler  should  always  be  thoroughly  inspected  before  it  is 
started  up.  In  the  case  of  the  locomotive  type  of  traction 
engine  boiler  (Fig  159)  the  crown  sheet  should  be  given  par- 
ticular attention. 


STEAM  GENERATION  AND  STEAM  BOILERS     41 

Problems:  Chapter  III 

1.  Sketch  and  explain  the  fundamental  parts  of  a  steam  power  plant. 

2.  Sketch  and  explain  the  use  of  the  various  kinds  of  pipe  fittings. 

3.  Explain,  using  clear  sketch,  the  construction  and  use  of  a  steam  gage. 

4.  Sketch  and  explain  the  action  of  some  form  of  feed  pump. 
6.  Sketch  and  explain  the  action  of  a  steam  injector. 

6.  Give  three  reasons  for  using  feed-water  heaters. 

7.  Explain  the  fundamentals  of  good  firing. 

8.  Calculate  the  heat  contained  in  71b.  of  dry  steam  at  100  Ib.  absolute. 

9.  If  the  steam  in  the  above  problem  contained  5  per  cent,  moisture, 
calculate  heat  contained  in  1  Ib. 

10.  Calculate  the  volume  of  3  Ib.  of  steam  at  atmospheric  pressure,  and 
also  at  a  pressure  of  150  Ib.  absolute. 

11.  If  steam  at  a  pressure  of  125  Ib.  absolute  has  a  temperature  of  390°F., 
is  it  saturated? 

12.  Taking  the  weight  of  a  gallon  of  water  as  8^  Ib.  and  using  the  values 
given  in  Tables  2  and  4,  compare  the  heat  units  contained  in  a  gallon  of  gaso- 
line and  kerosene. 

13.  If  a  ton  of  ice  melts  (at  a  temperature  of  32°F.)  in  24  hr.,  how  much 
heat  will  it  abstract  during  that  time  from  the  surrounding  substances? 

14.  Explain  the  meaning  of  boiler  horsepower.     Is  there  any  relation 
between  boiler  horsepower  and  engine  horsepower?     Explain  in  detail. 

16.  Give  directions  for  handling  a  boiler  plant. 

16.  What  should  be  done  in  case  of  low  water? 

17.  What  should  the  fireman  do  if  he  finds  that  the  steam-pressure  is 
excessive? 

18.  Give  directions  for  firing  bituminous  coal. 


CHAPTER  IV 
STATIONARY  STEAM  ENGINES 

Description  of  the  Steam  Engine. — A  steam  engine  is  a  motor 
which  utilizes  the  energy  of  steam.  It  consists  essentially  of  a 
piston  and  cylinder  with  valves  to  admit  and  exhaust  steam, 
a  governor  for  regulating  the  speed,  some  lubricating  system  for 
reducing  friction,  and  stuffing  boxes  for  preventing  steam  leakage. 

In  its  simplest  form,  the  steam  hammer,  the  steam  acting  on 
the  piston  lifts  weights  against  the  force  of  gravity. 


FIG.  33. — Engine  cylinder  and  steam  chest. 

In  the  steam  engine  working  as  a  motor  continuous  rotary 
motion  of  a  shaft  is  essential.  This  is  accomplished  by  the  inter- 
position of  a  mechanism  consisting  of  a  connecting  rod  and  crank, 
which  changes  the  to-and-fro  or  reciprocating  motion  of  the  piston 
into  mechanical  rotation  at  the  shaft.  A  steam  engine  in  which 
the  reciprocating  motion  of  the  piston  is  changed  into  rotary  mo- 
tion at  the  crank  is  called  a  reciprocating  steam  engine  to  differen- 
tiate this  form  of  motor  from  the  steam  turbine  to  be  described 
later. 

42 


STATIONARY  STEAM  ENGINES  43 

The  various  parts  of  a  steam  engine  are  illustrated  in  Figs.  33 
and  34. 

Steam  from  the  boiler  at  high  pressure  enters  the  steam  chest 
A,  Fig.  33,  and  is  admitted  through  the  ports  BB  alternately  to 
either  end  of  the  cylinder  by  the  valve  C.  The  same  valve 
also  releases  and  exhausts  the  steam  used  in  pushing  the  piston 
D.  E  is  the  cylinder  in  which  the  steam  is  expanded.  The 
motion  of  the  piston  D,  Fig.  34,  is  transmitted  through  the  piston 


FIG.  34. — Steam  engine. 

rod  F  to  the  crosshead  G,  and  through  the  connecting  rod  H 
to  the  crank  I  which  is  keyed  to  the  shaft  K. 

The  shaft  is  connected  directly,  or  by  means  of  intermediate 
connectors  such  as  belts  or  chains,  to  the  machines  to  be  driven. 

The  shaft  carries  the  flywheel  L,  the  function  of  which  is  to 
make  the  rate  of  rotation  as  uniform  as  possible  and  to  carry 
the  engine  over  dead-center.  The  dead-center  occurs  when  the 
crank  and  connecting  rod  are  in  a  straight  line  at  either  end 
of  the  stroke,  at  which  time  the  steam  acting  on  the  piston  will 
not  turn  the  crank.  A  flywheel  is  sometimes  used  as  a  driving 
pulley,  as  shown  in  Fig.  35. 

The  eccentric  shown  in  Fig.  35  also  rotates  with  the  shaft.  An 
eccentric  is  a  crank  of  special  form  which  imparts  reciprocating 
motion  to  the  valve  through  the  eccentric  rod  and  valve  stem. 


44 


FARM  MOTORS 


The  eccentricity  of  the  eccentric  is  the  distance  between  the 
center  of  the  eccentric  and  the  center  of  the  shaft.  The  travel  of 
the  valve  is  equal  to  the  throw  of  the  eccentric,  or  twice  the  eccen- 
tricity. Changing  the  eccentricity  changes  the  travel  of  the 
valve. 

Stuffing  boxes  which  prevent  the  escape  of  steam  around  the 
rods  are  illustrated  at  M  and  N  in  Figs.  33  and  34. 


Head          Innnnnnn  I 


'od  Box 

Valve  Stem  Driver 
Valve  Stem  Sevang 


FIG.  35. — Vertical  steam  engine. 

•***  *w 

The  size  of  a  steam  engine  is  given  in  terms  of  the  cylinder 
diameter  and  length  of  stroke  of  the  engine.  Thus  if  an  engine 
is  called  an  8-in.  by  10-in.  engine,  this  means  that  the  diameter 
of  its  cylinder  is  8  in.  and  its  stroke  or  piston  travel  is  10  in. 
>  Action  of  the  Plain  Slide  Valve. — The  action  of  the  plain  slide 
valve  will  now  be  taken  up  in  detail,  as  a  thorough  knowledge 
of  this  type  of  valve  will  enable  one  to  understand  all  other 
forms.  Referring  to  Fig.  36,  which  shows  a  section  of  a  cylinder 
with  the  slide  valve  in  mid-position,  A  and  B  are  the  steam  ports, 


STATIONARY  STEAM  ENGINES 


45 


which  lead  to  the  two  ends  of  the  cylinder;  C  is  the  exhaust 
space.  The  steam  ports  are  separated  from  the  exhaust  space 
by  the  two  bridges  D  and  E.  F  is  the  steam  chest.  V  is  a  plain 
slide  valve,  commonly  called  a  D  slide  valve.  The  amount  S 


FIG.  36. — Engine  cylinder  and  plain  slide  valve. 

that  the  valve  V  overlaps  the  outside  edge  of  the  port,  when  in  the 
middle  of  its  stroke,  is  called  the  steam  lap.  Similarly  the 
amount  by  which  the  valve  overlaps  the  inside  edge  of  the  port 


FIG.  37. — Admission. 


FIG.  38.— Cut-off. 


when  it  is  in  mid-position  is  called  the  exhaust  lap.     M  and  N 
are  the  steam  and  exhaust  pipes  respectively. 

The  four  valve  events  are:  admission,  cutoff,  release  and  com- 
pression. Admission  is  that  point  at  which  the  valve  is  begin- 
ning to  uncover  the  port,  as  shown  in  Fig.  37.  Cutoff  occurs 


46  FARM  MOTORS 

(Fig.  38)  when  the  valve  covers  the  port,  preventing  further  admis- 
sion of  steam.  This  is  followed  by  the  expansion  of  the  steam 
until  the  cylinder  is  communicated  with  the  exhaust  opening, 
at  which  time  release,  as  shown  by  Fig.  39,  occurs.  Compression 
occurs  when  communication  between  the  cylinder  and  exhaust 
opening  is  interrupted  (Fig.  40)  and  the  steam  remaining  in  the 
cylinder  is  slightly  compressed  by  the  piston.  The  valve  is  in 


FIG.  39. — Release.  FIG.  40. — Compression. 

the  same  position  at  cutoff  as  it  is  at  admission,  only  it  is  travel- 
ing in  the  opposite  direction.  Similarly  the  positions  of  the  valve 
are  the  same  at  release  and  compression. 

By  lead  is  meant  the  amount  that  the  port  is  uncovered  when 
the  engine  is  on  either  dead-center.  The  object  of  lead  is  to 
supply  full  pressure  steam  to  the  piston  as  soon  as  it  passes  the 
dead-center. 


FIG.  41. — Valve  without  laps. 

If  a  valve  is  constructed  without  laps,  as  shown  in  Fig.  41, 
steam  would  be  admitted  to  the  cylinder  at  one  end  or  the  other 
and  exhausted  at  the  opposite  end,  if  the  valve  is  moved  slightly 
in  either  direction.  This  would  mean  that  steam  admission 
at  one  end  would  take  place  throughout  the  entire  stroke  of  the 
piston  and  would  be  exhausted  from  the  opposite  end  at  the 
same  time.  It  is  evident  that  a  valve  without  laps  will  have 


STATIONARY  STEAM  ENGINES 


47 


no  cutoff  and  steam  will  not  be  used  expansively.  To  use  steam 
without  expansion  is  very  uneconomical  and  is  resorted  to  only 
in  direct-acting  steam  pumps.  For  best  economy  a  steam  engine 
should  be  provided  with  a  valve  which  cuts  off  at  about  one-third 
of  the  stroke. 

Types  of  Steam-engine  Valve  Gears. — The  simplest  type  of 
valve  for  steam  engines  is  the  single-slide  valve,  which  controls 


,Balance  Plate 

team.  .Chest  Cover 


Packing  Gland 


Piston 


/      Tacking 
Packing  Gland 


Lagging 

Tialon' 

FIG.,  42.— Balanced  valve.\ 


Counter  Bore 


the  admission  and  exhaust  of  steam  alternately  to  each  end  of  the 
cylinder.  The  form  shown  in  Fig.  33  is  called  a  p;ston  valve.  In 
the  position  shown  it  admits  steam  to  the  head  of  the  cylinder, 
the  end  farthest  away  from  crank,  and  at  the  same  time  exhausts 
the  steam  from  the  crank  end  of  the  cylinder. 

Still  a  simpler  type  of  valve,  the  plain  slide  valve,  often  used 
on  portable  and  on  traction  engines,  is  shown  in  Fig.  36.  The 
objection  to  this  type  of  valve  is  that  it  is  not  balanced,  and, 
either  the  friction  of  the  valve  on  its  seat  is  excessive,  or  the  valve 
allows  steam  to  leak  into  the  exhaust  space.  This  is  remedied 


48 


FARM  MOTORS 


by  the  piston  valve  shown  in  Fig.  33,  which  is  perfectly  balanced, 
or  by  some  form  of  balanced  slide  valves,  illustrated  in  Fig.  42, 
which  works  between  the  valve  seat  and  a  balance  plate  with 
an  accurate  mechanical  fit. 

Valve  Setting. — The  object  of  setting  valves  on  an  engine  is  to 
equalize  as  much  as  possible  the  work  done  on  both  ends  of  the 
piston.  A  valve  may  be  set  so  that  both  ends  have  the  same 
lead,  or  so  that  the  point  of  cutoff  is  the  same  at  both  ends. 

Before  a  valve  can  be  set,  the  dead-centers  for  both  ends  of 
the  engine  must  be  accurately  determined. 

The  method  of  setting  an  engine  on  dead-center  can  best  be 
understood  by  referring  to  Fig.  43.  H  represents  the  engine 


///////////^^^ 

FIG.  43.— Valve  setting. 

crosshead  which  moves  between  the  guides  marked  G,  N  is  the 
connecting  rod,  R  the  crank,  F  the  engine  flywheel,  and  0  a 
stationary  object. 

To  set  the  engine  on  dead-center,  turn  the  engine  in  the  direc- 
tion in  which  it  is  supposed  to  run,  as  shown  by  the  arrow,  until 
the  crosshead  is  near  the  end  of  its  head-end  travel,  and  make 
a  small  scratch  mark  on  the  crosshead  and  guide,  as  at  A.  At 
the  same  time  mark  the  edge  of  the  flywheel  and  the  stationary 
object  opposite  each  other,  as  at  B.  Turn  the  engine  past  dead- 
center,  in  the  same  direction  as  shown  by  the  arrow,  until  the 
mark  on  the  crosshead  and  that  on  the  guide  again  coincide  at  A, 
and  mark  the  flywheel  in  line  with  the  same  point  on  the  station- 
ary object,  obtaining  the  mark  C.  The  distance  between  the 
two  marks  on  the  flywheel  is  now  bisected  at  E.  If  the  mark  E 


STATIONARY  STEAM  ENGINES  49 

on  the  flywheel  is  now  placed  in  line  with  the  mark  on  the  station- 
ary object,  the  engine  will  be  on  the  head-end  dead-center. 
Similarly  the  crank-end  dead-center  can  be  found. 

The  stationary  object  may  be  a  wooden  board,  or  a  tram  may 
be  used  with  one  end  resting  on  the  engine  bedplate  and  with 
the  other  end  used  for  locating  the  marks  B,  C,  and  E  on  the 
flywheel. 

If  a  valve  is  to  be  set  for  equal  lead  on  both  ends,  set  the 
engine  on  the  dead-center  by  the  method  given  above,  remove 
the  steam-chest  cover,  and  measure  the  lead  at  that  end.  Move 
the  engine  forward  to  the  other  dead-center  and  measure  the  lead 
again.  If  the  lead  on  the  two  ends  is  not  the  same,  correct  half 
the  error  by  changing  the  length  of  the  valve  stem,  and  the  other 
half  by  moving  the  eccentric. 

To  set  an  engine  for  equal  cutoff,  turn  the  engine  until  the 
valve  cuts  off  at  one  end  and  mark  the  position  of  the  crosshead 
on  the  guides.  Then  turn  the  engine  until  cutoff  occurs  on  the 
opposite  end  and  again  mark  this  position  of  the  crosshead  on 
the  guides.  If  the  cutoff  occurs  earlier  at  one  end  than  at  the 
other,  shorten  the  valve  stem  until  the  cutoff  is  equalized  at 
both  ends. 

Steam-engine  Indicator  Cards. — In  general  the  best  method 
of  setting  valves  is  by  means  of  a  steam-engine  indicator,  ex- 
plained in  Chapter  II  and  illustrated  in  Fig.  1.  This  form  of 
instrument  shows  directly  the  action  of  the  steam  inside  the 
engine  cylinder,  recording  the  actual  pressure  at  each  interval  of 
the  stroke. 

An  indicator  card  taken  by  means  of  an  indicator  is  shown  in 
Fig.  44.  The  events  of  stroke  on  the  card  are  marked :  admission 
A,  cutoff  C,  release  R,  compression  K.  Fig.  45  shows  indicator 
cards  taken  from  two  ends  of  a  cylinder  with  a  valve  properly 
set,  while  Fig.  46  shows  indicator  cards  taken  from  an  engine 
where  the  valve  is  poorly  set. 

Losses  in  Steam  Engines. — The  main  losses  in  a  steam  engine 
are: 

1.  Loss  in   pressure  as  the  steam  is  transferred  from  the 
steam  boiler  to  the  engine  cylinder  due  to  the  throttling  action 
in  the  steam  pipe  and  ports. 

2.  Leakage  past  piston  and  valve. 


50 


FARM  MOTORS 


FIG.  44. — Steam-engine  indicator  card. 


3.  Losses  due  to  the  condensation  of  steam  in  the  cylinder 
during  part  of  the  stroke. 

4.  Radiation  losses  which  take  place  when  the  steam  passes 
through  the  steam  pipes  from  the  boiler  to  the  cylinder  and  also 
while  the  steam  is  in  the  cylinder. 

5.  Losses  of  heat  in  the 
exhaust  steam. 

6.  Mechanical  losses  due 
to  the  friction  of  the  mov- 
ing parts. 

Of  the  above  losses 
those  due  to  the  heat  car- 
ried away  in  the  exhaust 
steam  are  greatest  and  are 
usually  75  per  cent,  or 
more  of  the  heat  supplied 
in  the  steam.  Part  of  this 
heat  can  be  used  for  such 
purposes  as  the  heating  of 
feed  water  before  it  enters 
the  boiler,  for  heating 
buildings,  or  in  employing 
the  exhaust  steam  in  con- 
nection with  various  man- 
ufacturing processes. 

The  other  great  loss  is 
that  due  to  the  condensa- 
tion of  steam  which  takes 
place  when  the  entering 
steam  comes  into  contact 
with  the  cylinder  walls 
which  are  at  the  temp- 
erature of  the  exhaust 


FIG.  45. — Indicator  cards,  valves  prop- 
erly set. 


FIG.    46. — Indicator  cards,  valves  im- 
properly set. 


steam.  This  loss  can  be  reduced  to  a  considerable  extent  by 
having  the  steam  entering  the  cylinder  as  dry  as  possible. 
Another  method  for  reducing  this  loss,  which  is  used  in  connec- 
tion with  large  engines,  is  to  compound  the  engine. 

By  compounding  is  meant  the  subdivision  of  the  expansion 
of  the  steam  into  two  or  more  cylinders.     The  steam  on  leaving 


STATIONARY  STEAM  ENGINES  51 

the  boiler  enters  the  high-pressure  cylinder,  is  partly  expanded, 
and  then  enters  one  or  more  cylinders  where  its  expansion  is 
completed  to  the  exhaust  pressure.  The  range  of  pressures  in 
each  cylinder  of  a  compound  engine  being  less  than  is  the  case 
of  a  simple,  or  one-cylinder  engine,  the  temperature  difference 
between  the  incoming  and  the  outgoing  steam  is  less.  This  lower 
temperature  range  decreases  the  condensation  of  the  steam  in 
the  cylinder.  The  gain  in  economy  does  not  usually  compen- 
sate for  the  increased  first  cost  of  compound  engines  as  compared 
with  simple  engines  in  small  sizes. 

Radiation  losses  in  the  steam  pipes  leading  from  the  boilers 
to  the  engines  can  be  reduced  to  a  minimum  by  covering  the 
pipes.  A  good  pipe  covering  will  save  the  latent  heat  in  the 
steam  that  would  otherwise  be  lost,  will  keep  the  steam  drier, 
and  will  pay  for  itself  in  a  very  short  amount  of  time. 

The  cylinders  of  most  steam  engines  are  now  jacketed  with 
some  good  non-conductor  of  heat  and  this  loss  is  very  small. 

Mechanical  losses  in  steam  engines  can  be  reduced  by  proper 
lubrication.  Oil  can  be  applied  to  the  various  parts  by  separate 
sight-feed  lubricators  and  grease  cups.  Another  method  is  to 
connect  an  oil  tank  conveniently  located  with  the  various  parts 
by  adjustable  sight-feed  tubes,  allowing  different  rates  of  feed 
to  the  various  bearings.  Still  another  method  is  to  inclose  some 
of  the  parts  and  make  them  self-oiling. 

The  losses  due  to  leakage  past  the  piston  and  valves  are  usually 
very  small  in  well-designed  engines.  The  various  forms  of 
balanced  slide  valves  can  be  kept  tight  by  means  of  balance  plates. 

Steam-engine  Governors. — The  function  of  a  governor  is  to 
control  the  speed  of  rotation  of  a  motor  irrespective  of  the  power 
which  it  develops.  In  the  steam  engine,  the  governor  maintains 
a  uniform  speed  of  rotation  either  by  varying  the  initial  pressure 
of  the  steam  supplied,  or  by  changing  the  point  of  cutoff  and 
hence  the  portion  of  the  stroke  during  which  steam  is  admitted. 

Governors  which  regulate  the  speed  of  an  engine  by  varying 
the  initial  pressure  of  the  steam  supplied  to  the  engine  are  called 
throttling  governors.  This  is  the  simplest  form  of  governor  and 
is  used  mainly  on  engines  of  the  plain  slide-valve  type.  In 
Fig.  47  is  given  a  section  of  a  throttling  governor,  showing  details. 
This  form  of  governor  is  attached  to  the  steam  pipe  at  A  and  is 


52 


FARM  MOTORS 


connected  to  the  engine  cylinder  at  B,  so  that  the  steam  must 
pass  the  valve  V  before  entering  the  engine.  The  valve  V  is  a 
balanced  valve  and  is  attached  to  a  valve  stem  S,  at  the  upper 
end  of  which  are  two  balls  CC.  The  valve  stem  and  balls  are 
driven  from  the  engine  shaft  by  a  belt,  which  is  connected  to  the 
pulley  Pj  and  which  in  turn  runs  the  bevel  gears  D  and  E.  As 
the  speed  of  the  engine  is  increased  the  centrifugal  force  makes 
the  balls  fly  out,  and  in  doing  so  they  force  down  the  valve  stem 
S,  thus  reducing  the  area  of  the  opening  through  the  valve,  and 


FIG.  47. — Steam-engine  governor. 

the  steam  to  the  engine  is  throttled.  As  soon  as  the  engine  be- 
gins to  slow  down,  the  balls  drop,  increasing  the  steam  opening 
through  the  valve  V.  The  speed  at  which  the  steam  is  throttled 
can  be  changed  within  certain  limits  by  regulating  the  position 
of  the  balls  by  means  of  the  nut  N. 

Most  of  the  better  engines  are  governed  by  varying  the  point 
of  cutoff  and  hence  the  total  volume  of  steam  supplied  to  the 
cylinder. 

In  high-speed  automatic  engines  this  is  accomplished  by  some 


STATIONARY  STEAM  ENGINES 


53 


form  of  flywheel  governor  which  is  usually  placed  on  the  engine 
shaft,  and  which  controls  the  point  of  cutoff  by  changing  the 
position  of  the  eccentric. 

Engine  Details. — The  general  construction  of  steam-engine 
cylinders  can  be  seen  from  the  previous  illustrations.     Steam- 


FIG.  48.— Piston. 


FIG.  49. — Cross-head. 


FIG.  50. — Connecting  rod. 


engine  cylinders  are  made  of  cast  iron.  As  the  cylinder  wears 
it  has  to  be  rebored  so  as  to  maintain  true  inside  surfaces.  The 
thickness  of  the  cylinder  walls  not  only  should  be  strong  enough 
to  withstand  safely  the  maximum  steam  pressure,  but  should 
allow  for  reboring.  All  steam-engine  cylinders  should  be  pro- 


54  FARM  MOTORS 

vided  with  drip  cocks  at  each  end  in  order  to  drain  the  cylinder 
and  steam  chest  when  starting. 

A  good  piston  should  be  steam-tight  and  at  the  same  time 
should  not  produce  too  much  friction  when  sliding  inside  the 
engine  cylinder.  The  piston  is  usually  constructed  somewhat 
smaller  than  the  inside  diameter  of  the  engine  cylinder,  and  is 
made  tight  by  the  use  of  split  cast-iron  packing  rings.  In  Fig. 
48  is  illustrated  a  piston  with  its  packing  rings. 

The  general  construction  of  steam-engine  crossheads  is  illus- 


FIG.  51. — Eccentric  rod  and  strap. 


PIG.  52. — Main  bearings. 

trated  in  Fig.  49.  All  crossheads  should  be  provided  with  shoes 
which  can  be  adjusted  for  wear. 

Fig.  50  shows  a  connecting  rod.  It  is  connected  at  one  end 
with  the  crosshead  and  at  the  other  with  the  crankpin.  A  con- 
necting rod  should  be  so  constructed  that  the  wear  on  its  bearings 
can  be  taken  up.  This  is  usually  accomplished  by  wedges  and 
setscrews  as  illustrated. 

Some  engines  have  their  cranks  located  between  the  two  bear- 
ings of  an  engine,  and  are  called  center-crank  engines.  Engines 
which  have  the  cranks  located  at  the  end  of  the  shaft  and  on 
one  side  of  the  two  bearings  are  called  side-crank  engines. 


STATIONARY  STEAM  ENGINES 


55 


The  eccentric  is  a  special  form  of  crank.  It  is  usually  set 
somewhat  more  than  90°  ahead  of  the  crank  and  gives  motion 
to  the  valve  or  valves  in  the  steam  chest  of  the  engine.  The 
eccentric  is  a  cast-iron  disc  through  which  the  shaft  passes  and 
which  gives  motion  to  the  valve.  Fig.  51  shows  an  eccentric 
rod  and  strap. 

The  main  bearings  of  steam  engines  are  illustrated  in  Fig.  52. 
These  bearings  are  usually  made  in  three  or  four  parts  and  can 
be  adjusted  for  wear  by  means  of  wedges  and  setscrews  fastened 
with  locknuts. 

Lubricators. — The  subject  of  lubricating  the  moving  parts  of 


FIG.  53. — Grease  cups.         FIG.  54. — Automatic  grease  cup. 


an  engine  was  treated  to  some  extent  in  connection  with  the 
discussion  of  mechanical  losses  in  steam  engines. 

Bearings  may  be  lubricated  by  grease  cups  illustrated  by 
Figs.  53  and  54.  The  first  type  is  used  on  stationary  bearings, 
the  grease  being  forced  out  by  screwing  the  cap  down  by  hand. 
The  type  illustrated  in  Fig.  54  is  automatically  operated,  and  is 
used  for  the  lubrication  of  crankpins. 

If  oil  is  used,  a  plain  oil  cup,  illustrated  in  Fig.  55,  can  be  em- 
ployed, or  some  form  of  sight-feed  lubricator,  as  shown  in  Fig. 
56.  By  means  of  the  sight-feed  types  the  flow  of  oil  can  be 
regulated  and  the  drops  of  oil  issuing  from  the  lubricator  can 
be  seen. 


56 


FARM  MOTORS 


For  the  lubrication  of  steam-engine  cylinders  some  form  of 
sight-feed  automatic  steam  lubricator,  as  illustrated  in  Fig.  57, 
should  be  employed.  This  form  of  lubricator  is  used  to  introduce 
a  heavy  oil  into  the  steam  entering  the  cylinder.  This  oil  is  a 


FIG.  55. — Plain  oil  cup.     FIG.  56. — Sight-feed  lubricator. 


FIG.  57. — Sight-feed  automatic  lubricator. 

specially  refined  heavy  petroleum  oil  which  will  neither  decom- 
pose, vaporize,  or  burn  when  exposed  to  the  high  temperature  of 
steam.  Steam  from  the  pipe  leading  to  the  cylinder  B  is  admitted 
through  the  pipe  F  to  the  condensing  chamber  E,  where  it  is  con- 
densed and  falls  through  the  pipe  P  to  the  bottom  of  the  chamber 


STATIONARY  STEAM  ENGINES 


57 


A.  The  oil  which  is  contained  in  chamber  A  rises  to  the  top, 
is  forced  through  the  tube  S,  ascends  in  drops  through  the 
water  in  the  gage  glass  H,  and  into  the  steam  pipe  K  leading  to 
the  steam  chest.  The  amount  of  oil  fed  is  regulated  by  the 
needle  valve  E.  T  shows  the  amount  of  oil  in  the  chamber  A. 


FIG.  58. — Hand  oil  pump. 

In  order  to  fill  the  chamber  A,  the  valves  on  the  pipes  F  and 
H  are  closed,  the  water  is  drained  out  through  G,  and  the  cap 
D  is  removed  for  receiving  the  oil. 

Fig.  58  shows  a  hand  oil  pump  which  is  sometimes  used  to 
admit  oil  into  the  cylinder  of  an  engine  when  starting. 

Steam  Separators. — The  function  of  a  steam  separator  is  to 
remove  any  water  which  may  be  con- 
tained in  the  steam  before  it  enters  the 
engine  cylinder.  A  separator  placed  in 
the  exhaust  pipe  of  an  engine  will  remove 
a  large  part  of  the  oil,  making  the  exhaust 
steam  more  suitable  for  heating,  manu- 
facturing purposes,  or  for  use  in  steam 
boilers  after  condensation. 

The  importance  of  having  the  steam 
entering  the  engine  cylinder  as  dry  as 
possible  was  explained  in  an  earlier  part 
of  this  chapter.  A  good  steam  separator, 
if  of  sufficient  size,  will  insure  fairly  dry 
steam  and  should  be  used  in  connection 
with  all  stationary  steam  engines. 

Fig.  59  shows  in  section  one  form  of 
steam  separator.  The  wet  steam  enters 
at  A,  strikes  the  deflecting  plates,  its  velocity  is  decreased  and 
the  entrained  water,  which  is  heavier  than  the  steam,  falls  to 
the  bottom  and  is  removed  at  C  by  means  of  a  trap.  The 
dry  steam  passes  out  at  B. 


59. — Steam    sepa- 
rator. 


58 


FARM  MOTORS 


The  Steam  Locomobile  or  Buckeymobile. — The  locomobile, 
as  built  in  Europe,  and  the  Buckeymobile  of  the  United  States, 
is  a  self-contained  power  plant,  which  consists  of  a  compound 


steam  engine  mounted  upon  an  internally  fired  boiler.  An  in- 
sulated sheet-metal  smoke  box  incloses  both  engine  cylinders,  a 
superheater,  all  steam  piping  and  valves,  and  a  reheater  which 
imparts  heat  to  the  steam  as  it  passes  from  the  high-  to  the  low- 


STATIONARY  STEAM  ENGINES  59 

pressure  cylinder.  This  arrangement  utilizes  the  heat  in  the 
flue  gases  for  superheating  the  steam  before  it  enters  the  engine 
cylinder,  for  reheating  the  steam  between  the  high-  and  the  low- 
pressure  cylinder,  for  reducing  heat  losses  within  the  engine  and 
for  cutting  down  the  radiation  losses  of  the  entire  power 
plant. 

The  steam  from  the  engine  exhausts  through  a  feed-water 
heater  into  a  condenser,  where  it  is  condensed  (converted  into 
water)  by  direct  contact  with  cold  water  or  by  contact  with  tubes 
through  which  cold  water  circulates. 

Fig.  60  shows  a  longitudinal  section  of  a  Buckeymobile  with  the 
various  parts  named. 

This  form  of  power  plant  has  found  a  large  field  of  application 
in  Europe  on  account  of  its  compactness  and  good  fuel  economy. 
The  Buckeymobile,  in  small  sizes,  will  no  doubt  in  time  be  used 
to  a  considerable  extent  in  rural  communities  in  connection  with 
flour  mills,  for  irrigation  pumping  plants  and  for  electric  light 
plants  in  small  towns.  The  principle  of  this  type  of  power  plant 
should  also  find  successful  application  in  connection  with  steam 
traction  engines. 

Steam  Turbines. — The  steam  turbine  differs  from  the  steam 
engine  described,  in  that  it  produces  rotary  motion  directly  and 
without  any  reciprocating  parts.  It  consists  of  a  stationary 
part  and  one  or  more  wheels  with  vanes  which  are  rotated  by 
steam  striking  the  vanes.  The  elastic  force  of  the  steam,  instead 
of  acting  on  a  piston,  is  exerted  on  the  steam  itself,  producing  a 
drop  in  pressure  and  a  steam  jet  of  high  velocity. 

The  steam  turbine  is  best  adapted  for  the  driving  of  elec- 
trical generators,  centrifugal  pumps  and  air  compressors,  cream 
separators  and  other  machinery  requiring  a  high-speed  rotation. 

In  large  sizes  the  steam  turbine  is  somewhat  more  economical 
than  the  reciprocating  steam  engine  and  occupies  considerably 
less  space.  The  steam  turbine  requires  no  internal  lubrication, 
and  thus  the  exhaust  steam  can  be  used  again  in  the  boiler  with- 
out requiring  oil  filtration.  For  large  power  plants  the  steam 
turbine  has  several  other  advantages. 

The  action  of  one  form  of  steam  turbine  used  for  the  driv- 
ing of  cream  separators  is  illustrated  in  Fig.  61.  A,  B,  C  and 
D  are  stationary  nozzles  in  which  the  steam  is  completely  ex- 


60 


FARM  MOTORS 


panded  and  strikes  the  vanes  V,  giving  a  direct  rotary  motion 
to  the  wheel  W  and  also  to  the  shaft  S. 

Installation  and  Care  of  Steam  Engines. — Foundations  for 
stationary  steam  engines  are  usually  put  in  by  the  purchaser,  the 
manufacturer  furnishing  complete  drawings  for  that  purpose. 
Drawings  of  a  board  template  are  also  included.  A  template  is 


FIG.  61. — Steam  turbine. 

a  wooden  frame  which  is  used  in  locating  the  foundation  bolts 
and  for  holding  them  in  position  while  building  the  foundation. 

Before  starting  on  the  foundation  a  bed  should  be  prepared 
for  receiving  it.  The  depth  of  bed  depends  on  the  soil.  If  the 
soil  is  rocky  and  firm,  the  foundation  can  be  built  without  much 
difficulty.  When  the  soil  is  very  soft,  piles  may  have  to  be 
driven.  The  ground  for  receiving  the  piles  should  be  excavated 
to  a  depth  of  about  2  ft. 

The  wooden  template  is  then  constructed  from  the  drawings, 
holes  being  bored  for  the  insertion  of  foundation  bolts. 

Foundations  may  be  built  of  masonry  or  of  concrete.  If  of  con- 
crete the  mixture  should  consist  of  1  part  of  cement,  2  parts  of 
sharp  sand  and  4  parts  of  crushed  stone.  The  stone  should  be  of 


STATIONARY  STEAM  ENGINES 


61 


a  size  as  will  pass  through  a  2-in.  ring.  In  starting  on  a  con- 
crete foundation,  a  wooden  frame  of  the  exact  shape  of  the  founda- 
tion is  built.  This  template  is  then  placed  in  position  in  the 
manner  shown  by  Fig.  62,  and  the  bolts  are  put  in,  the  heads  of 
the  bolts  being  at  the  bottom  in  recesses  of  cast-iron  anchor  plates 
marked  P.  Often  the  foundation  bolts  are  threaded  at  both 
ends  and  the  anchor  plates  are  held  in  place  by  square  nuts.  A 
piece  of  pipe  should  be  placed  around  each  bolt,  so  as  to  allow 


FIG.  62. — Foundation  in  the  process  of  construction. 

the  bolts  to  be  moved  slightly  to  pass  through  the  holes  in  the 
engine  bedplate,  in  case  an  error  should  occur  in  the  placing  of 
the  bolts,  or  in  the  location  of  the  bolt  holes  in  the  engine 
bedplate. 

With  the  frame,  template  and  foundation  bolts  in  place,  the 
concrete  can  now  be  poured  and  tamped  down.  After  the  con- 
crete has  set,  the  template  is  removed  and  the  foundation  is  made 
perfectly  level.  It  is  well  to  allow  a  concrete  foundation  to  set 
several  weeks  before  placing  the  full  weight  of  the  engine  on  it. 

When  the  foundation  is  ready,  the  engine  is  placed  in  position 
and  leveled  by  means  of  wedges.  The  nuts  on  the  bolts  are  now 
screwed  down  and  the  engine  is  grouted  in  place  by  means  of 
neat  cement,  this  serving  to  fill  any  crevices  and  to  give  the 
engine  a  perfect  bearing  on  the  foundation. 

After  erecting  the  engine  and  all  its  auxiliaries,  including  pipes, 
valves,  cocks  and  lubricators,  all  the  parts  should  be  carefully 
examined  and  cleaned,  and  a  coating  of  oil  should  be  applied  to 
all  rubbing  surfaces,  cylinder  oil  being  used  for  the  wearing 
parts  in  the  valve  chest  and  cylinder. 


62  FARM  MOTORS 

Before  the  engine  is  operated  for  the  first  time,  it  is  well  to 
loosen  the  nuts  and  bolts,  adjust  bearings,  and  turn  the  engine 
over  slowly  until  an  opportunity  has  been  given  for  any  in- 
equalities due  to  tool  and  file  marks  to  be  partially  eliminated, 
and  also  to  prevent  heating  that  might  occur  if  there  was  an 
error  in  adjustment. 

When  the  engine  is  ready  to  start,  the  boiler  valve  should  be 
slowly  opened  to  allow  the  piping  to  warm  up,  but  leaving  the 
drain  cock  in  the  steam  pipe,  above  the  steam  chest,  open  to 
permit  the  escape  of  condensation.  While  the  piping  is  being 
warmed  up  all  the  grease  cups  and  lubricators  are  filled.  Before 
opening  the  throttle  valve,  all  cylinder  and  steam-chest  drain 
cocks  should  be  opened  to  expel  water,  and  the  flow  of  oil  started 
through  the  various  lubricators.  The  throttle  valve  is  then 
opened  gradually,  and  both  ends  of  the  engine  warmed  up. 
This  can  be  accomplished  in  the  case  of  a  single- valve  engine  by 
turning  the  engine  over  slowly  by  hand  to  admit  steam  in  turn 
to  each  end  of  the  cylinder.  In  starting  a  Corliss  engine  the 
eccentric  is  unlocked  from  the  pin  on  the  wristplate  and  the 
wristplate  is  rocked  by  hand  sufficiently  to  allow  steam  to  pass 
through  each  set  of  valves.  The  drain  cocks  are  closed  soon 
after  the  throttle  is  wide  open  and  the  engine  is  gradually 
brought  up  to  speed,  provided  steam  is  blowing  through. 

When  ^topping  an  engine,  close  the  throttle  valve.  As  soon 
as  the  engine  stops,  close  the  lubricators,  wipe  clean  the  various 
parts,  examine  all  bearings  and  leave  the  engine  in  perfect 
condition  ready  to  start. 

The  above  instructions  apply  to  non-condensing  engines. 
If  the  engine  is  to  be  operated  condensing,  the  circulating  and 
air  pumps  should  be  started  while  the  engine  is  warming  up. 
The  other  directions  apply  with  slight  modifications  to  all  types 
of  steam  engines. 

In  regard  to  daily  operation,  cleanliness  is  of  great  importance. 
No  part  of  the  engine  should  be  allowed  to  become  dirty  and  all 
parts  must  be  kept  free  from  rust.  It  is  well  to  draw  off  all  the 
oil  from  bearings  quite  frequently  and  to  clean  them  with 
kerosene  before  refilling  with  fresh  oil.  In  starting  it  is  well  to 
give  the  various  parts  plenty  of  oil,  but  the  amount  should  be  de- 
creased as  the  engine  warms  up.  An  excess  of  oil  should  be  avoided. 


STATIONARY  STEAM  ENGINES  63 

Competent  engine  operators  usually  make  a  practice  of  going 
over  and  cleaning  every  bearing,  nut,  and  bolt,  immediately  on 
shutting  down.  This  practice  not  only  keeps  the  engine  in  first- 
class  condition,  as  regards  cleanliness,  but  enables  the  operator 
to  detect  the  first  indication  of  any  defect  that,  if  overlooked, 
might  result  seriously. 

If  a  knock  develops  in  a  steam  engine,  it  should  be  located 
and  remedied  at  once.  Knocking  is  usually  due  to  lost  motion 
in  bearings,  worn  journals  or  crosshead  shoes,  water  in  the 
cylinder,  loose  piston,  or  to  poor  valve  setting.  Locating  knocks 
in  steam  engines  is  to  a  great  extent  a  matter  of  experience  and 
no  definite  rules  can  be  laid  down  which  will  meet  all  cases. 

However,  the  beginner  may,  by  careful  attention  to  the 
machine,  learn  to  trace  out  the  location  of  a  knock  in  a  com- 
paratively short  time.  He  must,  however,  bear  in  mind  that 
he  cannot  rely  on  his  ear  for  locating  it,  as  the  sound  produced 
by  a  knock  is,  in  many  cases,  tramsmitted  along  the  moving 
parts,  and  apparently  comes  from  an  entirely  different  point. 

A  knock,  due  to  water  in  the  cylinder,  is  usually  sharp  and 
crackling  in  its  nature,  while  that  in  the  case  of  a  crank  or  a  cross- 
head  pin  is  more  in  the  nature  of  a  thud.  If  the  knock  should  be 
due  to  looseness  of  the  main  bearings,  the  location  may  be  de- 
tected by  carefully  watching  the  flywheel,  while  if  the  cross- 
heads  are  loose  in  the  guides  the  observer  may  be  able  to  detect 
a  motion  crossways  of  the  crosshead,  but  it  is  not  likely  that  he 
can  do  this  with  accuracy  in  the  case  of  a  high-speed  engine,  and 
the  crosshead  should  be  tested  when  the  engine  is  at  rest.  In 
no  case  should  any  adjustment  be  made  in  bearings  or  moving  parts 
of  an  engine  unless  the  machine  is  at  standstill  or  being  turned  by 
hand;  never  when  under  its  own  power. 

The  heating  of  a  bearing  is  always  due  to  one  of  five  causes : 

1.  Insufficient  lubrication  due  to  insufficient  quantity  of  oil, 
wrong  kind  of  oil,  or  lack  of  proper  means  to  distribute  the  oil 
about  the  bearings. 

2.  The  presence  of  dirt  in  the  bearings. 

3.  Bearings  out  of  alignment. 

4.  Bearings   improperly   adjusted;   they   may   be   either  too 
tight  or  too  loose. 

5.  Operation  in  a  place  where  the  temperature  is  excessive. 


64  FARM  MOTORS 

In  case  a  bearing  should  run  hot  and  it  is  very  undesirable  to 
shut  down,  it  is  oftentimes  possible  to  keep  going  by  a  liberal 
application  of  cold  water  upon  the  entire  heated  surface  or  sur- 
faces. It  is  sometimes  possible  to  stop  heating  by  changing 
from  machine  oil  to  cylinder  oil  which  has  a  higher  flash  point. 

Should  a  bearing,  particularly  a  large  one,  be  overheated  to 
the  extent  that  it  is  necessary  to  shut  down  the  engine,  do  not 
shut  down  suddenly  or  allow  the  bearing  to  stand  any  length  of 
time  without  attention.  This  is  particularly  important  in  the 
case  of  babbitted  bearings,  as  the  softer  metal  of  the  bearings 
will  tend  to  become  brazed  to,  or  fused  with,  the  harder  metal 
of  the  shaft,  and  it  may  be  necessary  to  put  the  engine  through 
the  shop  before  it  can  be  used  again. 

In  case  of  the  necessity  of  shutting  down  for  a  hot  bearing, 
first  remove  the  load,  then  permit  the  engine  to  revolve  slowly 
under  its  own  steam  until  the  bearing  is  sufficiently  cool  to  per- 
mit the  bare  hand  to  rest  on  it. 

The  presence  of  water  in  the  cylinder  is  always  a  source  of 
danger,  and  care  should  be  taken  that  the  water  of  condensation 
is  thoroughly  drained  from  the  cylinder  when  the  engine  is  first 
started,  at  shutting  down,  and  at  regular  intervals  throughout 
the  operation.  An  accumulation  of  water  may  readily  result 
in  the  blowing  out  of  a  cylinder  head  with  its  resultant  loss  to 
property  and  possibly  of  life.  There  are  several  appliances  now 
on  the  market  which  automatically  safeguard  the  cylinder  head 
by  providing  a  weak  point  in  the  drain  system  which  will  relieve 
the  excess  pressure  before  the  cylinder  head  gives  way. 

Problems:  Chapter  IV 

1.  Sketch  and  explain  the  action  of  the  plain  slide-valve  engine. 

2.  Explain  in  detail  how  to  set  the  valve  of  a  steam  engine. 

3.  Discuss  the  losses  in  steam  engines. 

4.  Sketch  and  explain  some  form  of  steam-engine  governor. 

6.  Sketch  and  explain  construction  and  use  of  the  common  grease  cup,  the 
eight-feed  type  of  lubricator  and  steam-engine  cylinder  sight-feed  automatic 
lubricator. 

6.  Explain  the  fundamental  details  of  the  steam  Buckeymobile. 

7.  Explain,  with  sketches,  the  action  of  a  steam  turbine. 

8.  Give  directions  for  starting  and  stopping  steam  engines. 

9.  Give  directions  for  the  care  of  a  steam  engine. 

10.  Explain  how  to  prevent  the  heating  of  bearings. 


CHAPTER  V 
GAS  AND  OIL  ENGINES 

The  Internal-combustion  Engine, — The  internal-combustion 
engine,  commonly  called  a  gas  engine,  differs  from  the  steam 
engine,  in  that  the  transformation  of  the  heat  energy  of  the  fuel 
into  work  takes  place  within  the  engine  cylinder.  The  fuel  may 
be  gasoline,  kerosene,  crude  petroleum,  alcohol,  illuminating 
gas,  or  some  form  of  power  gas. 

In  order  to  form  an  explosive  mixture  in  the  cylinder,  air  must 
be  mixed  in  certain  proportions  with  the  fuel,  and  this  can  be  ac- 
complished only  when  the  fuel  is  in  the  gaseous  state,  or  is  a  mist 
of  liquid  fuel  easily  vaporized  at  ordinary  temperatures.  Thus 
the  essential  difference  among  internal-combustion  engines  using 
the  various  fuels  is  in  the  construction  of  the  device  for  preparing 
the  fuel  before  it  enters  the  engine  cylinder.  If  the  fuel  is  a  gas, 
only  a  stop  valve  is  necessary  between  the  source  and  the  gas- 
engine  admission  valve.  The  devices  for  preparing  liquid  fuels 
depend  on  the  character  of  the  fuel,  a  heavy  fuel  requiring  heat 
while  a  volatile  fuel  is  easily  vaporized  at  ordinary  temperatures 
by  being  broken  up  into  a  fine  mist.  If  the  fuel  is  in  the  solid 
form,  like  coal,  it  must  be  converted  into  a  gas  by  the  use  of  a 
gas  producer,  to  be  described  later,  before  it  can  be  used  in  the 
gas-engine  cylinder. 

After  the  mixture  is  drawn  into  the  cylinder,  it  is  prepared  by 
compressing  and  intimately  mixing  the  fuel  with  the  air  at  one 
end  of  the  engine  cylinder.  This  highly  compressed  combustible 
mixture  of  air  and  fuel  is  burned  within  the  cylinder  against  the 
face  of  the  .piston.  The  heat  liberated  by  the  burning  gases 
causes  these  gases  to  expand,  the  pressure  within  the  cylinder  is. 
increased  and  the  piston  is  driven  out  toward  the  other  end  of 
the  cylinder.  The  motion  of  the  piston  is  changed  into  rotary 
motion  at  the  crankshaft  through  the  interposition  of  the  con- 
necting rod  and  crank.  The  crankshaft  can  be  connected  directly 
to  the  machines  to  be  driven  or  through  mechanical  connectors, 

such  as  belts  and  chains. 

65 

5 


66  FARM  MOTORS 

The  internal-combustion  engine,  in  small  sizes,  is  much  more 
economical  than  the  steam  power  plant.  The  average  small 
steam  power  plant  converts  less  than  5  per  cent,  of  the  heat 
energy  in  the  fuel  into  useful  work.  A  small  oil  engine  which 
develops  a  horsepower  on  1  Ib.  of  gasoline  per  hour  converts 
nearly  15  per  cent,  of  the  heat  energy  available  in  the  fuel  into 
work. 

The  Gas-engine  Cycle. — The  series  of  events  which  are 
essential  for  carrying  out  the  transformation  of  heat  into  work 
is  called  the  cycle  of  an  engine.  The  gas-engine  cycle  mostly 
used,  the  Otto  cycle,  comprises  five  events,  which  are: 

1.  The  mixture  of  fuel  and  air  must  be  drawn  into  the  engine 
cylinder. 

2.  The  mixture  must  be  compressed. 

3.  The  mixture  must  be  ignited. 

4.  The  ignited  mixture  expands  doing  work. 

5.  The  cylinder  must  be  cleaned  of  burned  gases  in  order  to 
receive  a  fresh  mixture. 

The  above  five  events  in  the  order  explained  are  usually  called: 
suction,  compression,  ignition,  expansion,  and  exhaust. 

There  is  another  commercial  gas-engine  cycle,  the  Diesel, 
which  is  used  in  certain  types  of  oil  engines.  The  Diesel  cycle 
also  requires  five  events,  and  differs  from  the  Otto  cycle  in  that 
air  without  fuel  is  compressed  in  the  engine  cylinder  to  such  a 
great  pressure  that  the  temperature  resulting  is  sufficiently 
high  to  ignite  the  fuel  automatically,  as  it  is  sprayed  by  an 
auxiliary  pump  into  the  engine  cylinder. 

The  compression  pressures  carried  in  engines  working  on  the 
Diesel  cycle  are  about  500  Ib.  per  square  inch,  while  those 
carried  in  engines  working  on  the  Otto  cycle  and  with  the  same 
fuels  are  55  to  90  Ib.  per  square  inch. 

Classification  of  Gas  Engines. — Gas  engines  are  divided  into 
two  classes,  according  to  the  number  of  piston  strokes  required 
to  carry  out  the  five  events  of  the  gas-engine  cycle.  To  one  class 
belong  all  engines  which  require  four  complete  strokes  of  the 
piston,  or  two  complete  revolutions  of  the  crankshaft  to  carry 
out  the  five  events  of  the  gas-engine  cycle.  These  engines  are 
called  four-stroke  cycle  engines.  The  two-stroke  cycle  engine 
works  on  the  same  gas-engine  cycle  as  the  four-stroke  cycle 


GAS  AND  OIL  ENGINES 


67 


engine,  only  the  mechanism  is  modified  so  as  to  complete  the  five 
events  in  two  strokes  of  the  piston. 

The  Four-stroke  Cycle. — The  action  of  an  internal-combustion 
engine  working  on  the  four-stroke  Otto  cycle  is  illustrated  in 
Figs.  63  to  67. 


Inlet 'Valve 


FIG.  63.— Suction. 

1.  Suction  of  the  mixture  of  air  and  gas  through  the  inlet 
valve  takes  place  during  the  complete  outward  stroke  of  the 
piston,  the  exhaust  valve  being  closed.  This  is  shown  in  Fig. 
63.  This  stroke  of  the  piston  is  called  the  suction  stroke. 


Inlet  Valve 


FIG.  64. — Compression. 

2.  On  the  return  stroke  of  the  piston,  shown  in  Fig.  64,  both 
the  inlet  and  exhaust  valves  remain  closed  and  the  mixture  is 
compressed  between  the  piston  and  the  closed  end  of  the  cylinder. 
This  is  called  the  compression  stroke.  Just  before  the  compres- 


© 


FIG.  65. — Ignition. 

sion  stroke  of  the  piston  is  completed,  the  compressed  mixture  is 
ignited  by  a  spark  (Fig.  65)  and  rapid  combustion,  or  explosion, 
takes  place. 

3.  The  increased  pressure  within  the  cylinder  due  to  the  rapid 
combustion  of  the  mixture  drives  the  piston  on  its  second  for- 


68 


FARM  MOTORS 


ward  stroke,  which  is  the  power  stroke.  This  is  shown  in  Fig.  66. 
This  power  stroke,  or  working  stroke,  is  the  only  stroke  in  the 
cycle  during  which  power  is  generated.  Both  valves  remain 


Exhaust  Valve* 


FIG.  66. — Expansion. 


closed  until  the  end  of  the  power  stroke,  when  the  exhaust  valve 
opens  and  provides  communication  between  the  cylinder  and 
the  atmosphere. 


Inlet  Valve 


Spark  Plug 


Exhaust  Valve- 


FIG.  67.— Exhaust. 

4.  The  exhaust  valve  remains  open  during  the  fourth  stroke 
called  the  exhaust  stroke,  Fig.  67,  during  which  the  burned 
gases  are  driven  out  from  the  cylinder  by  the  return  of  the  piston. 


Suction  Stroke 

FIG.  68. — Gas-engine  indicator  card. 


An  indicator  diagram,  taken  from  a  four-stroke  cycle  engine, 
using  gasoline  as  fuel,  is  illustrated  in  Fig.  68.  IB  is  the  suction 
stroke,  BC  the  compression  stroke,  CD  shows  the  ignition  event, 
DE  is  the  power  stroke  and  El  is  the  exhaust  stroke.  The 


GAS  AND  OIL  ENGINES  69 

direction  of  motion  of  the  piston  during  each  stroke  is  illustrated 
in  each  case  by  arrows.  Lines  AF  and  AG  were  added  to  the 
indicator  diagram;  the  first  is  the  atmospheric  line,  while  AG  is 
the  line  of  pressures.  From  Fig.  68  it  will  be  noticed  that  part 
of  the  suction  stroke  occurs  at  a  pressure  lower  than  atmos- 
pheric. The  reason  for  this  is  that  a  slight  vacuum  is  created 
in  the  cylinder  by  the  piston  moving  away  from  the  cylinder 
head.  This  vacuum  helps  to  draw  or  suck  the  mixture  into  the 
cylinder. 

The  engine  working  on  the  four-stroke  cycle  requires  two  com- 
plete revolutions  of  the  crankshaft,  or  four  strokes  of  the  piston 
to  produce  one  power  stroke  or  working  stroke.  The  other  three 
are  not  only  idle  strokes,  but  power  is  required  to  move  the 
piston  through  these  strokes,  and  this  has  to  be  furnished  by 
storing  extra  momentum  in  heavy  flywheels.  Several  attempts 
we're  made  from  time  to  time  to  produce  an  internal-combustion 
engine  by  modifying  the  Otto  or  Diesel  gas-engine  cycles,  so  that 
the  working  stroke  would  occur  more  frequently.  This  has 
resulted  in  the  so-called  two-stroke  cycle  engine,  to  be  explained 
in  the  next  section,  which  completes  the  cycle  in  two  strokes, 
requiring  only  one  complete  revolution  of  the  crank. 

The  Two -stroke  Cycle  Engine. — The  two-stroke  cycle  engine 
carries  out  the  gas-engine  cycle  in  two  strokes  by  precompress- 
ing  the  mixture  of  fuel  and  air  in  a  separate  chamber,  and  by 
having  the  events  of  expansion,  exhaust  and  admission  occur 
during  the  same  stroke  of  the  piston.  The  precompression  of 
the  mixture  is  accomplished  in  some  engines  by  having  a  tightly 
closed  crank  case,  and  in  other  types  by  closing  the  crank  end  of 
the  cylinder,  and  providing  a  stuffing  box  for  the  piston  rod. 
Large  two-stroke  cycle  engines  are  usually  made  double-acting 
and  an  additional  cylinder  is  provided  for  the  precompression 
of  the  mixture. 

The  principle  of  the  two-stroke  cycle  internal-combustion 
engine  is  illustrated  in  Fig.  69.  On  the  upward  stroke  of  the 
piston  P,  a  partial  vacuum  is  created  in  the  crank  case  C,  and 
the  explosive  mixture  of  fuel  and  air  is  drawn  in  through  a  valve 
at  A.  At  the  same  time  a  mixture  previously  taken  into  the 
upper  part  of  the  cylinder  W  is  compressed.  Near  the  end  of 
this  compression  stroke,  the  mixture  is  fired  from  a  spark  pro- 


70 


FARM  MOTORS 


duced  by  the  spark  plug  S.  This  produces  an  increase  in  pres- 
sure which  drives  the  piston  on  its  downward  or  working  stroke. 
The  piston  descending  compresses  the  mixture  in  the  crank 
case  to  several  pounds  above  atmospheric,  the  admission  valve 
at  A  being  closed  as  soon  as  the  pressure  in  the  crank  case  ex- 


FIQ.  69. — Two-stroke  cycle  engine. 

ceeds  atmospheric.  When  the  piston  is  very  near  the  end  of  its 
downward  stroke,  it  uncovers  the  exhaust  port  at  E  and  allows 
the  burned  gases  to  escape  into  the  atmosphere.  The  piston 
continuing  on  its  downward  stroke  next  uncovers  the  port  at  /, 
allowing  the  slightly  compressed  mixture  in  the  crank  case  C  to 
rush  into  the  working  part  of  the  cylinder  W. 

The  distinctive  feature  of  the  two-stroke  cycle  engine  is  the 


GAS  AND  OIL  ENGINES  71 

absence  of  valves.  The  transfer  port  I  from  the  crank  case  C 
to  the  working  part  of  the  cylinder  W,  as  well  as  the  exhaust 
port  E,  are  opened  and  closed  by  the  piston. 

Comparison  of  Two-stroke  Cycle  and  Four-stroke  Cycle 
Engines. — To  offset  the  advantages  resulting  from  fewer  valves, 
less  weight  and  greater  frequency  of  working  strokes,  the  two- 
stroke  cycle  engine  is  usually  less  economical  in  fuel  consumption 
and  not  as  reliable  as  the  four-stroke  cycle  engine.  As  the  inlet 
port  I  is  opened  while  the  exhaust  of  the  gases  takes  place  at  E, 
there  is  always  some  chance  that  part  of  the  fresh  mixture  will 
pass  out  through  the  exhaust  port.  Closing  the  exhaust  port 
too  soon  will  cause  a  decrease  in  power  and  efficiency,  on  account 
of  the  mixing  of  the  inert  burned  gases  with  the  fresh  mixture. 
By  carefully  proportioning  the  size  and  location  of  the  ports,  and 
by  providing  the  piston  with  a  lip  L  (Fig.  69)  to  direct  the  in- 
coming mixture  toward  the  cylinder  head,  the  above  losses  may 
be  decreased.  In  any  case  the  scavenging  of  the  cylinder 
cannot  be  as  complete  in  the  two-stroke  cycle  as  in  the  four- 
stroke  cycle  engine,  where  one  full  stroke  of  the  piston  is  allowed 
for  the  removal  of  the  exhaust  gases.  The  four-stroke  cycle 
engine  also  has  the  advantages  of  wider  use  and  of  longer  period 
of  development. 

The  two-stroke  cycle  engine  can  be  made  to  run  in  either 
direction  by  a  simple  modification  of  the  ignition  timing  mechan- 
ism. This  feature,  and  its  light  weight,  makes  the  two-stroke 
cycle  engine  especially  adaptable  for  the  propulsion  of  small 
boats.  For  stationary  purposes,  in  small  and  medium  sizes, 
and  for  the  propulsion  of  traction  engines,  automobiles  and 
other  vehicles,  the  four-stroke  cycle  engine  is  usually  to  be 
preferred  on  account  of  its  reliability  and  somewhat  better  fuel 
economy. 

Gas-engine  Fuels. — Fuels  for  internal-combustion  engines 
may  be  classified  as  solid,  liquid  and  gaseous.  The  value  of  a 
fuel  for  gas-engine  use  depends  on  the  amount  of  heat  liberated 
when  the  fuel  is  burned,  on  the  cost  of  the  fuel,  and  on  the  cost 
of  preparing  the  fuel  for  use  in  the  gas-engine  cylinder. 

As  was  explained  in  the  earlier  part  of  this  chapter,  the  fuel 
entering  the  gas-engine  cylinder  must  be  in  the  form  of  a  vapor 
or  a  gas.  For  this  reason  where  a  gaseous  fuel  can  be  obtained 


72  FARM  MOTORS 

at  low  cost,  the  complications  of  the  engine  mechanism  are 
reduced.  In  or  near  the  natural  gas  regions,  no  other  gas-engine 
fuel  is  a  competitor  of  the  natural  gas.  Also  in  connection  with 
certain  industrial  processes,  certain  gaseous  fuels  are  obtained  as 
byproducts  and  are  utilized  with  good  results  in  gas  engines. 
Illuminating  gas  is  usually  too  expensive  for  a  gas-engine  fuel. 

Where  solid  fuels  are  cheap  and  petroleum  oils  are  expensive, 
an  artificial  gas,  suitable  for  gas  engine  use,  can  be  generated  in 
a  gas  producer.  A  gas  producer  consists  essentially  of  a  tall 
shell  filled  with  coal,  coke,  or  with  some  other  solid  fuel  and  sup- 
plied with  a  blast  of  air  and  steam.  Due  to  the  thickness  of  the 
fuel  bed  the  combustion  of  the  fuel  is  incomplete  and  a  com- 
bustible gas  is  formed.  The  steam  supplied  with  the  blast 
enriches  the  gas  and  prevents  the  formation  of  clinker  by  keeping 
down  the  temperature  of  the  fuel  bed.  Producer  gas  is  not  used 
at  the  present  time  as  a  fuel  for  farm  motors,  although  experi- 
ments are  being  carried  on  with  a  gas  producer  as  a  possible 
power  plant  for  gas  traction  engines. 

As  a  portable  engine  for  small  powers,  the  internal-combustion 
engine  using  some  liquid  fuel  has  the  greatest  field  of  applica- 
tion. Such  engines  are  especially  suitable  for  intermittent  work 
and  are  ideal  for  farm  use. 

The  liquid  fuels  used  in  internal-combustion  engines  are  gaso- 
line, kerosene,  crude  petroleum,  fuel  oil  and  alcohol. 

Gasoline  and  Other  Distillates  of  Crude  Petroleum. — Gaso- 
line and  kerosene  are  among  the  lighter  distillates  of  crude  petro- 
leum. The  so-called  distillates  are  obtained  by  boiling  or 
refining  crude  petroleum  in  large  retorts  or  stills,  and  condensing 
the  vapors  which  are  driven  off  at  various  temperatures. 

The  vapors  which  are  condensed  into  gasoline  are  driven  off 
at  temperatures  of  140°  to  160°F.  The  various  grades  of  kerosene 
are  the  condensed  vapors,  driven  off  at  temperatures  of  250°  to 
400°F.,  and  the  heavy  oils  are  driven  off  at  still  higher  temperatures. 

Of  all  petroleum  distillates,  gasoline  is  the  most  important 
fuel  for  small  internal-combustion  engines.  The  yield  of  gaso- 
line, however,  is  very  small  in  comparison  with  the  heavier  dis- 
tillates. By  refining  American  petroleum,  an  average  of  less  than 
15  per  cent,  of  gasoline  is  obtained  and  usually  about  50  per  cent, 
of  kerosene.  This  makes  gasoline  more  expensive  than  other 


GAS  AND  OIL  ENGINES 


73 


petroleum  fuels.  However,  as  a  fuel  for  small  and  portable 
engines  it  has  the  advantages  of  quick  starting  and  greater 
reliability,  which  more  than  make  up  for  the  greater  cost.  Proc- 
esses are  now  being  perfected  for  extracting  greater  quantities 
of  gasoline  from  crude  petroleum,  and  there  is  little  doubt  that 
gasoline  will  remain  for  many  years  to  come  the  most  important 
fuel  for  small  internal-combustion  engines  and  for  gasoline 
automobiles. 

Gasoline  has  a  flash  point  of  10°  to  20°F.  This  means  that  it 
forms  an  inflammable  vapor  at  that  low  temperature,  provided  a 
sufficient  supply  of  air  is  present.  For  this  reason  care  must  be 
taken  in  the  handling  of  gasoline.  A  good  storage  tank  free 
from  leaks  and  placed  underground  contributes 
greatly  to  the  safety,  as  well  as  to  the  econom- 
ical use  of  gasoline.  When  filling  a  gasoline 
storage  tank  or  in  handling  gasoline,  care 
must  be  taken  not  to  have  any  unprotected 
flame  nearby.  In  case  gasoline  takes  fire  at 
the  engine  or  at  the  storage  tank,  it  is  best 
to  extinguish  it  by  means  of  wet  sawdust. 
Sand  or  dirt  will  do  in  an  emergency,  but  if  it 
finds  its  way  into  the  engine  cylinder,  it  may 
cause  considerable  damage  by  cutting  the  rubbing 
surfaces. 

Kerosene,  which  can  be  secured  in  greater 
quantities  than  gasoline,  and  which  has  a  rather 
limited  market,  is  the  fuel  next  to  gasoline, 
among  the  products  of  crude  petroleum,  for  use 
in  oil  engines.  This  fuel  is  more  difficult  to 
vaporize  at  ordinary  temperatures  and  presents 
a  more  difficult  problem  when  used  in  oil  en- 
gines than  does  gasoline. 

The  flash  point  of  kerosene  is  70°  to  150°F.,  depending  on  the 
grade.  As  the  flash  point  of  oil  is  a  measure  of  its  safety,  a  kero- 
sene of  a  lower  flash  point  than  120°F.  is  dangerous  for  use  as  an 
illuminating  oil  in  lamps.  The  lower  the  flash  point  of  an  oil 
the  better  it  is  for  gas-engine  use,  as  less  heat  is  required  to  vapor- 
ize it  ready  for  use  in  the  engine  cylinder. 

Very  light  gasoline  has  a  specific  gravity  of  from  0.65  to  0.74. 


FIG.  70.— Hy- 
drometer. 


74  FARM  MOTORS 

TABLE    5. — RELATION    BETWEEN    SPECIFIC    GRAVITY,   THE   BAUME   HY- 
DROMETER SCALE,  AND  THE  WEIGHT  PER  GALLON 


Specific 
gravity 

Degrees 
Baum6 

Pounds  per 
gallon 

Specific 
gravity 

Degrees 
Baum6 

Pounds  per 
gallon 

1.000 

10 

8.336 

0.775 

51 

6.462 

0.993 

11 

8.277 

0.771 

52 

6.428 

0.986 

12 

8.220 

0.767 

53 

6.394 

0.979 

13 

8.161 

0.763 

54 

6.358 

0.972 

14 

8.104 

0.759 

55 

6.324 

0.966 

15 

8.051 

0.755 

56 

6.290 

0.959 

16 

7.997 

0.751 

57 

6.258 

0.953 

17 

7.944 

0.747 

58 

6.212 

0.947 

18 

7.891 

0.743 

59 

6.195 

0.940 

19 

7.837 

0.739 

60 

6.163 

0.934 

20 

7.785 

0.736 

61 

6.133 

0.928 

21 

7.736 

0.732 

62 

6.101 

0.922 

22 

7.687 

0.728 

63 

6.070 

0.916 

23 

7.638 

0.724 

64 

6.038 

0.911 

24 

7.590 

0.721 

65 

6.006 

0.905 

25 

7.541 

0.717 

66 

5.975 

0.899 

26 

7.493 

0.713 

67 

5.946 

0.893 

27 

7.444 

0.710 

68 

5.916 

0.887 

28 

7.395 

0.706 

69 

5.886 

0.881 

29 

7.347 

0.703 

70 

5.856 

0.876 

30 

7.298 

0.699 

71 

S.&27 

0.870 

31 

7.254 

0.696 

72 

5.797 

0.865 

32 

7.210 

0.692 

73 

5.771 

0.860 

33 

7.166 

0.689 

74 

5.743 

0.854 

34 

7.122 

0.686 

75 

5.715 

0.849 

35 

7.079 

0.682 

76 

5.688 

0.844 

36 

7.038 

0.679 

77 

5.659 

0.840 

37 

6.998 

0.676 

78 

5.632 

0.835 

38 

.6.696 

0.672 

79 

5.603 

0.830 

39 

6.918 

0.669 

80 

5.576 

0.825 

40 

6.878 

0.666 

81 

5.548 

0.820 

41 

6.839 

0.662 

82 

5.517 

0.816 

42 

6.804 

0.658 

83 

5.487 

0.811 

.      43 

6.760 

0.655 

84 

5.457 

0.806 

44 

6.721 

0.651 

85 

5.427 

0.802 

45 

6.683 

0.648 

86 

5.402 

0.797 

46 

6.644 

0.645 

87 

5.374 

0.793 

47 

6.608 

0.642 

88 

5.353 

0.788 

48 

6.571 

0.639 

89 

5.316 

0.784 

49 

6.534 

0.639 

90 

5.304 

0.779 

50 

6.498 

GAS  AND  OIL  ENGINES  75 

The  specific  gravity  of  kerosene  is  0.78  to  0.86,  of  crude  oil  0.87 
to  0.90,  and  of  fuel  oil  0.90  to  0.94.  The  specific  gravity  of  petro- 
leum fuels  is  usually  given  in  degrees  of  the  Baum6  hydrometer. 
Commercial  gasoline  will  test  from  50°  to  65°Be.  This  means 
that  when  a  hydrometer  is  placed  in  the  gasoline  (Fig.  70),  it 
will  sink  to  a  depth  as  will  indicate  50°  to  65°,  the  lighter  gasoline 
showing  the  greater  value.  The  relations  existing  between  the 
specific  gravity  of  various  liquid  fuels,  the  degrees  on  the  Baume 
hydrometer,  and  the  weight  of  a  fuel  in  pounds  per  gallon  are 
given  in  Table  5. 

A  study  of  Table  5  shows  that  the  weight  per  gallon  of  the 
heavier  oil  is  greater  than  that  of  the  lighter  oils.  Since  the 
calorific  value  per  pound  of  the  various  petroleum  fuels  is  very 
nearly  the  same  (see  Table  4,  Chapter  III),  and  liquid  fuels  are 
bought  by  the  gallon,  it  is  evident  that  the  total  heat  in  a  gallon 
of  kerosene  or  in  that  of  the  still  heavier  oil,  is  much  greater  than 
the  heat  in  a  gallon  of  gasoline.  Kerosene  for  farm  use  has  the 
further  advantages  over  gasoline  in  that  it  can  be  obtained  every- 
where, is  cheaper,  can  be  used  for  illumination  in  lamps  and  is  not 
so  dangerous. 

Any  good  gasoline  engine  can  be  easily  changed  into  one  suit- 
able for  kerosene  fuel.  Such  engines  are  started  on  gasoline  and 
changed  over  to  kerosene  as  soon  as  the  cylinder  walls  become 
hot.  Several  types  of  engines,  to  be  described  later,  will  start 
on  kerosene  and  will  also  operate  on  crude  petroleum  and  on 
fuel  oil.  The  first  cost  of  such  engines  is  greater  than  that  of  a 
gasoline  engine,  and  these  are  used  mainly  in  sizes  of  25  hp. 
and  larger  for  the  driving  of  pumps  in  irrigation  plants,  and  also 
in  connection  with  electric  light  plants  for  towns  or  cities. 

The  various  types  of  gas  tractors,  to  be  described  in  another 
chapter,  are  usually  started  on  gasoline  and  operate  with  kerosene 
or  with  solar  oil,  which  is  a  heavier  distillate  than  kerosene. 

In  general,  an  engine  running  on  petroleum  fuel  other  than 
gasoline  is  more  difficult  to  start  and  requires  greater  care  and 
more  frequent  cleaning  of  valves  and  pistons.  For  small  engines 
gasoline  has  sufficient  advantages  to  give  it  the  preference  to  the 
cheaper  petroleum  fuels. 

Alcohol  as  a  Fuel  for  Gas-engine  Use. — Alcohol  as  a  fuel  for 
gas-engine  use  has  many  advantages  as  compared  with  the 


76  FARM  MOTORS 

petroleum  distillates.  It  is  less  dangerous  than  gasoline,  its 
products  of  combustion  are  odorless,  and  it  lends  itself  to  greater 
compression  pressures  than  do  the  various  petroleum  fuels. 
Experiments  show  that  an  engine  designed  to  stand  the  com- 
pression pressures  before  ignition  most  suitable  for  alcohol  will 
develop  about  30  per  cent,  more  power  than  a  gasoline  engine  of 
the  same  size,  stroke  and  speed.  Alcohol,  when  used  as  a  fuel  in 
the  ordinary  gasoline  engine,  and  with  the  common  compression 
pressures  for  gasoline  fuel,  will  show  a  much  poorer  economy  than 
gasoline,  or  kerosene.  Engines  operating  with  alcohol  fuel  are 
difficult  to  start  and  the  operation  at  variable  loads  is  less  certain 
than  with  gasoline  fuel. 

Several  years  ago,  when  the  internal  revenue  tax  was  removed 
from  alcohol,  so  denatured  as  to  destroy,  its  character  as  a  bever- 
age, it  was  expected  that  denatured  alcohol  would  become  a  very 
important  fuel  for  use  in  gas  engines.  Its  price  up  to  this  date, 
however,  has  been  so  much  higher  than  that  of  gasoline,  the  most 
expensive  of  petroleum  fuels,  that  its  use  in  gas  engines  is  still  out 
of  the  question.  It  is  probable  that,  as  the  cost  of  the  petroleum 
distillates  increases,  and  processes  are  developed  for  producing 
denatured  alcohol  at  a  low  price,  the  alcohol  engine  will  come  into 
prominence  as  a  motor  for  farm  use. 

American  denatured  alcohol  consists  of  100  volumes  of  ethyl 
(grain)  alcohol,  mixed  with  10  volumes  of  methyl  (wood)  alcohol 
and  with  0.5  volume  of  benzol. 

The  specific  gravity  of  denatured  alcohol  is  about  0.795  and 
its  calorific  value  is  about  two-thirds  that  of  petroleum  fuels. 
Alcohol  requires  less  air  for  combustion  than  do  petroleum  fuels. 
Theoretically,  the  calorific  value  of  a  cubic  foot  of  explosive 
mixtures  of  alcohol  and  of  gasoline  is  about  the  same.  Actual 
tests  show  that  the  fuel  economy  per  horsepower  is  about  the 
same  for  both  fuels  provided  the  compression  pressures  before 
ignition  are  best  suited  for  the  particular  fuel  used.  In  gasoline 
engines,  a  compression  pressure  of  about  75  Ib.  is  used,  while  the 
alcohol  engine  gives  best  results,  as  far  as  economy  and  capacity 
are  concerned,  when  the  compression  pressure  before  ignition  is 
180  Ib.  per  square  inch. 

Essential  Parts  of  a  Four-stroke  Cycle  Gas  Engine.— The 
essential  parts  of  a  gas  engine  are  illustrated  in  Fig.  71.  The  fuel 


GAS  AND  OIL  ENGINES 


77 


from  the  liquid  fuel  tank  T  is  supplied  to  the  mixing  valve  or 
carburetor  through  the  fuel-regulating  valve  G.  The  air,  through 
the  air  pipe  A,  enters  the  same  carburetor  and  is  thoroughly 
mixed  with  the  fuel.  The  mixture  of  air  and  vaporized  fuel  enters 
the  engine  cylinder  C  through  the  inlet  valve  V  as  the  piston  P 
moves  on  the  suction  stroke.  The  mixture  is  then  compressed, 
and  ignited  by  an  electric  spark  produced,  at  the  spark  plug  Z,  by 
current  furnished  from  the  battery  B.  The  ignition  of  the  mix- 
ture is  followed  by  the  power  stroke.  The  reciprocating  motion 
of  the  piston  P  is  communicated,  through  the  connecting  rod  R,  to 


FIG.  71. — Parts  of  a  four-stroke  cycle  gas  engine. 

the  crank  N}  and  is  changed  into  rotary  motion  at  the  crankshaft 
S.  The  crankshaft  S,  while  driving  the  machinery  to  which  it  is 
connected,  also  turns  the  valve  gear  shaft,  sometimes  called  the 
two-to-one  shaft,  through  the  gears  X  and  Y.  The  gear  Y  turns 
once  for  every  two  revolutions  of  the  crank,  and  near  the  end  of 
the  power  stroke  opens  the  exhaust  valve  E  through  the  rod  D 
pivoted  at  0  In  larger  engines  this  valve  gear  shaft  also  opens 
and  closes  the  admission  valve  V  and  operates  the  fuel  pump 
and  ignition  system.  As  the  temperatures  resulting  from  the  igni- 
tion of  the  explosive  mixture  is  usually  over  2,000°F.,  some 
method  of  cooling  the  walls  of  the  cylinder  must  be  used,  in  order 
to  facilitate  lubrication,  to  prevent  the  moving  parts  from  being 
twisted  out  of  shape  and  to  avoid  the  ignition  of  the  explosive 
mixture  at  the  wrong  time  of  the  cycle.  One  method  of  cooling 


78  FARM  MOTORS 

gas  engines  is  to  jacket  the  cylinder  J,  that  is,  to  construct  a 
double-walled  cylinder  and  circulate  water  between  the  two  walls, 
through  the  jacket  space.  The  base  U  supports  the  various 
parts  of  the  engine;  the  flywheel  W  carries  the  engine  through 
the  idle  strokes.  Besides  the  above  details,  every  gas  engine  is 
usually  provided  with  lubricators  L  for  the  cylinder  and  bear- 
ings, and  with  a  governor  for  keeping  the  speed  constant  at 
variable  loads. 

The  majority  of  farm  gas  engines  are  of  the  single-acting  type. 
This  means  the  combustion  (burning)  of  the  fuel  takes  place  at 
one  end  of  the  piston  only. 

The  various  parts  of  horizontal  and  vertical  gasoline  engines 
are  illustrated  and  named  in  Figs.  72  and  73. 

Carburetors  for  Gasoline  Engines. — The  function  of  a  car- 
buretor is  to  vaporize  the  gasoline,  mix  it  with  the  correct  pro- 
portion of  air  to  form  an  explosive  mixture  and  then  deliver  the 
mixture  to  the  engine  cylinder. 

A  mixture  of  fuel  and  air  in  the  proper  proportions  is  one  of  the 
most  important  factors  essential  to  the  economical  and  reliable 
operation  of  a  gasoline  engine.  If  too  little  air  is  present,  or  if 
the  mixture  is  too  rich,  the  fuel  will  not  burn  completely.  This 
will  result  in  loss  of  power,  the  exhaust  from  the  engine  will  be 
darkened  and  odorous,  and  the  unburned  fuel  may  explode  in  the 
exhaust  pipe,  when  it  meets  more  air.  If  the  mixture  has  too 
little  gasoline,  or  is  too  lean,  it  will  be  slow-burning.  In  fact, 
it  may  still  be  burning  when  the  inlet  valve  opens  on  the  suction 
stroke,  and  the  flame,  flashing  back  through  the  inlet  valve  into 
the  carburetor,  may  produce  what  is  commonly  called  "  back- 
firing." Faulty  timing  of  valves,  or  a  badly  leaking  valve,  may 
also  cause  back-firing. 

In  some  early  forms  of  carburetors  the  air  was  passed  over  the 
surface  of  the  gasoline  on  its  way  to  the  engine  and  became 
saturated  with  the  fuel.  In  another  type,  called  the  bubbling 
carburetor,  the  air  was  made  to  bubble  through  the  fuel.  The 
objection  to  these  types  of  carburetors  is  that  the  air  combines 
with  only  the  more  volatile  portion  of  the  fuel,  leaving  the  heavier 
constituents  not  vaporized. 

The  modern  carburetors  are  of  the  spray  or  nozzle  type,  that 
is,  the  gasoline  is  injected  into  the  entering  air  through  a  nozzle 


GAS  AND  OIL  ENGINES 


79 


FIG.  72. — Hopper-cooled  gasoline  engine. 


Gasoline 
Throttle 


Inlet 


SuctionEi 


RllerCap 


FIG.  73. — Vertical  gasoline  engine. 


80 


FARM  MOTORS 


in  the  form  of  a  finely  divided  spray.  In  the  best  forms  of  spray 
carburetors  the  fuel  is  delivered  to  the  nozzle  at  constant  pres- 
sure by  maintaining  the  fuel  at  a  constant  level  in  the  carburetor, 
either  by  means  of  an  overflow  pipe  or  by  a  float. 

To  the  first  type  belong  the  mixer  valves,,  or  pump-feed  car- 
buretors, in  which  constant  pressure  is  obtained  by  a  pump  and 
an  overflow  pipe  keeping  the  height  of  the  fuel  at  a  constant 
level  in  a  small  reservoir.  This  type  of  carburetor  is  well  suited 
for  stationary  and  for  semiportable  engines.  Pump-feed  carbu- 
retors are  also  used  to  a  limited  extent  on  traction  engines.  This 
form  of  carburetor  is  well  adapted  for  a  fuel  supply  which  is 
located  in  a  tank  underground  and  at  a  considerable  distance. 

For  automobiles,  boats,  portable  engines  and  for  traction 
engines  the  float-feed  type  of  carburetor  is  best-adapted.  In  this 
type  of  carburetor  the  gasoline  is  admitted  to  a  float  chamber,  by 

gravity,  from  a  tank  placed  above  the 
carburetor.  The  gasoline  flows  out  of 
the  float  chamber  by  a  spray  nozzle,  the 
level  of  the  fuel  in  the  chamber  being 
regulated  by  a  copper  or  by  a  cork 
float  which  operates  the  gasoline  valve. 
Most  carburetors  of  the  float-feed  type 
are  automatic  in  their  action  in  that  the 
quality  of  the  mixture  is  regulated,  by 
auxiliary  air  inlet  valves,  to  suit  the 
speed  at  which  the  motor  is  running. 

One  form  of  mixer  valve,  or  pump- 
feed  carburetor,  is  illustrated  in  Fig. 
74.  A  pump  operated  by  the  valve 
gear  shaft  of  the  engine  forces  the  gas- 
oline through  the  supply  pipe  A  to  the  reservoir  B.  0 
is  the  overflow  or  return  pipe  which  maintains  the  fuel 
at  a  constant  level  in  the  reservoir,  and  slightly  below  the 
point  at  which  the  needle  valve  V  enters  the  gasoline  nozzle 
N.  When  the  piston  of  the  engine  starts  on  the  suction  stroke, 
a  partial  vacuum  is  created  in  the  cylinder;  the  inlet  valve  is 
opened  and  a  current  of  air  is  forced  by  the  atmospheric  pressure 
into  the  cylinder.  This  current  of  air  enters  through  the  air 
pipe  C,  attains  a  high  velocity,  and  carries  with  it  into  the  cylinder 


FIG.  74. — Pump-feed  car- 
buretor. 


GAS  AND  OIL  ENGINES 


81  ' 


a  portion  of  the  gasoline  vapor.  This  is  the  reason  why  the  air 
passage  of  a  carburetor  is  so  arranged,  that  the  velocity  of  the 
air  is  increased  as  it  passes  around  the  gasoline  spray  nozzle. 
The  greater  the  velocity  of  the  air  at  the  nozzle  the  more  vapor 

Exhaust  Port2--..    ^_  WatirJacKef^      jW1tr,OutJef' 
FxJrffvsftefaffa 


Igniter  Opening    |(O 
""Gasoline  Throttle 


FIG.  75. — Pump-feed  carburetor  and  engine  cylinder. 

is  carried  into  the  engine  cylinder.  When  starting  an  engine  by 
hand  with  this  form  of  carburetor,  a  damper  or  throttle  in  the 
air  pipe  is  closed,  so  that  the  velocity 
of  the  air  is  increased  sufficiently  to 
admit  the  fuel  to  the  cylinder.  The  rel- 
ative positions  of  the  air  throttle  and 
mixer  are  illustrated  in  Fig.  75. 

Another  form  of  spray  nozzle  carburet- 
ors is  illustrated  in  Fig;  76.  Air  enters 
at  the  lower  opening  C,  gasoline  flows  in 
at  (5),  and  the  mixture  of  the  air  and 
fuel  leaves  the  mixer  valve  at  B.  The 
amount  of  gasoline  fed  is  regulated  by 
adjusting  the  needle  valve  at  P. 
When  the  engine  piston  moves  on  its 
outward  stroke,  the  disc  F  is  raised  by 
suction,  drawing  in  a  charge  of  air,  through  the  seat  open- 
ing and  past  the  gasoline  port,  into  the  mixing  chamber 
above  F.  The  lift  and  movement  of  the  valve  F,  and 
consequently  the  quantity  of  the  mixture  to  the  cylinder, 
is  regulated  by  the  stem  (6).  The  gasoline  is  supplied  from  a 
tank  above  the  carburetor.  This  form  of  carbureter  is  much 
used  for  two-stroke  cycle  engines,  as  it  facilitates  easy  starting, 


FIG.  76. — Gravity  car- 
buretor. 


82 


FARM  MOTORS 


but  is  somewhat  dangerous  on  account  of  the  possibility  of 

gasoline  leakage. 

In  small  stationary  engines  the  form  shown  in  Fig.  77  is  often 

used.     This  carburetor  consists  essentially  of  a  needle  valve  N, 

which  regulates  the  fuel,  and  a  check  ball  valve  B  which  maintains 

the  level  of  the  fuel. 

Automatic  or  float-feed  carburetors  are  provided  with  two' 

chambers,  one  a  float  chamber 
in  which  a  constant  level  of  the 
fuel  is  maintained  by  means  of  a 
float,  the  other  a  mixing  chamber 
through  which  the  air  passes 
and  mixes  with  the  fuel.  The 
float  and  mixing  valves  may  be 
placed  side  by  side,  or  the  two 
chambers  may  be  constructed 

T-,     -_  concentric:  that  is,  the  float  is 

FIG.  77. — Suction-feed  carburetor. 

placed  around  the  spray  nozzle. 

The  concentric  type  keeps  the  fuel  at  the  predetermined  level 
much  better  than  the  carburetor  with  the  chambers  side  by  side. 


FIG.  78. — Kingston  carburetor. 

The  concentric  float-feed  type  of  carburetor  is  illustrated  in 
Fig.  78.  F  represents  the  float,  which  operates  the  float  valve 
V  and  regulates  the  amount  of  gasoline  entering  the  float  chamber 
W  through  fuel  inlet  at  G.  The  air  inlet  to  the  carburetor  is 


GAS  AND  OIL  ENGINES  83 

at  A.  S  is  the  gasoline-adjusting  screw  which  regulates  the 
needle  valve.  The  mixing  chamber  around  the  top  of  the  spray- 
ing nozzle  J  is  constructed  so  as  to  increase  the  velocity  of  the 
air  at  that  point.  This  part  is  called  the  throat  or  Venturi  tube 
of  the  carburetor.  The  amount  of  mixture  which  is  allowed  to 
pass  to  the  engine  cylinder  is  regulated  by  the  throttle  E.  As 
the  throttle  E  is  opened  and  the  speed  of  the  motor  increases,  the 
velocity  of  the  air  at  the  Venturi  passage  becomes  great  and  too 
much  fuel  is  pulled  in  by  the  air.  To  overcome  this,  carburetors 


FIG.  79. — Stromberg  carburetor. 

of  this  type  are  arranged  with  auxiliary  valves  which  are  con- 
trolled by  the  balls  M.  These  auxiliary  valves  admit  more  air 
as  the  speed  of  the  motor  increases,  diluting  the  mixture  before 
it  is  allowed  to  enter  the  engine  cylinder. 

A  float-feed  carburetor  with  the  two  chambers  side  by  side  is 
illustrated  in  Fig.  79.  In  the  float  chamber  is  placed  a  float  F 
which  operates  the  float  valve  V  and  regulates  the  amount  of 
fuel  entering  the  float  chamber  W.  The  main  air  inlet  is  at  A. 
When  the  float  chamber  becomes  filled  with  gasoline  to  a  certain 
level,  the  float  closes  the  needle  valve  F,  and  'the  flow  of  fuel  is 
stopped.  The  fuel  from  the  float  chamber  enters  the  mixing 
chamber  M,  at  the  right,  and  is  picked  up  by  the  air  entering  at  A. 
The  mixture  passes  to  the  engine  cylinder  through  the  throttle  E. 


84 


FARM  MOTORS 


The  auxiliary  air  valve  0  is  operated  by  a  spring  and  regulates 
the  quality  of  the  mixture  in   proportion  to  the  speed  of  the 


PIG.  80. — Bennett  carburetor. 


•    FIG.  81. — Schebler  carburetor. 

engine  and  in  a  manner  similar  to  the  ball  valves  in  the  carburetor 
of  Fig.  78.  In  some  forms  of  carburetors  an  enlarged  main  air 
inlet  takes  the  place  of  the  auxiliary  valve.  In  others,  the  con- 


GAS  AND  OIL  ENGINES  85 

nection  to  the  throttle  regulates  the  fuel  needle  valve,  or  the  air 
inlet,  to  suit  the  speed  of  the  engine  and  the  load  on  the  engine. 
Two  other  forms  of  float-feed  carburetors  are  shown  in  Figs. 
80  and  81.  The  parts  of  these  carburetors  are  designated  by  the 
same  letters  as  the  similar  parts  in  Figs.  78  and  79. 

The  concentric  type  of  carburetor  is  usually  preferred  on  ac- 
count of  the  fact  that  the  pressure  on  the  spray  nozzle  can  be 
kept  more  nearly  constant  in  this  type  than  in  the  carbureter 
where  the  float  and  mixing  chambers  are  placed  side  by  side. 

Floats  for  carburetors  are  made  either  of  cork  or  of  metal. 
The  hollow  metal  float  is  more  expensive  and  is  more  liable  to 
leak.  Cork  floats,  when  covered  thoroughly  with  shellac,  will 
not  lose  their  buoyancy,  but  there  is  some  danger  that  particles 
may  become  detached  from  the  cork  and  clog  the  passages  leading 
to  the  spray  nozzle. 

The  carburetor  float  chamber  is  usually  provided  with  a  pet- 
cock  at  its  lowest  point  (P  in  Fig.  79),  for  drawing  off  poorer 
grades  of  gasoline  and  also  water. 

In  automobile  practice,  multiple-jet  carburetors  are  sometimes 
used.  The  multiple-jet  carburetor  has  two  or  more  spray  nozzles 
and  this  enables  the  engine  to  draw  the  correct  proportion  of  fuel 
and  air  at  high  speeds. 

The  action  of  the  carburetor,  Fig.  80,  is  that  of  a  multiple-jet 
type.  In  starting,  this  form  operates  as  a  surface  carburetor, 
but  the  mixture  becomes  diluted  as  the  engine  speeds  up. 

Most  float-feed  carburetors  are  provided  with  some  hand- 
operated  method  for  priming  the  carburetor.  This  is  accom- 
plished by  depressing  the  float,  so  that  an  excess  of  gasoline  may 
be  allowed  to  enter  the  mixing  chamber,  Another  method  is  by 
throttling  the  air. 

To  overcome  carburetor  troubles  on  account  of  climatic  con- 
ditions, or  where  low-grade  gasoline  is  used,  the  carburetor  should 
be  jacketed  by  hot  water.  A  hot-air  connection  to  the  carburetor 
will  also  overcome  this  difficulty.  In  automobiles  in  which  the 
ther mo-syphon  system  of  water  circulation  is  employed,  exhaust 
gases  from  the  engine  are  used  for  jacketing  the  carburetor, 
instead  of  hot  water.  Hot  jackets  are  also  advantageous  in  cold 
weather  and  prevent  the  use  of  rich  mixtures  and  the  consequent 
low  fuel  economy. 


86 


FARM  MOTORS 


Carbureting  Kerosene  and  the  Heavier  Fuels. — The  various 
forms  of  carburetors  described  cannot  be  used  for  kerosene  or 
for  the  heavier  petroleum  fuels,  as  these  fuels  are  less  volatile 
than  gasoline  at  ordinary  temperatures  and  pressures.  The 
heavier  the  fuel  the  more  heat  is  required  to  vaporize  it. 

A  kerosene  carburetor,  used  on  some  forms  of  traction  engines,  is 


S/ow  Speed 


High  Speect 
Ac/jusfmertf 

FIG.  82. — Kerosene  carburetor. 

illustrated  in  Fig.  82;  the  parts  of  this  carburetor  are  designated 
by  the  same  letters  as  similar  parts  in  Fig.  78. 

An  ordinary  gasoline  engine  will  operate  with  kerosene  fuel, 
if  started  on  gasoline,  but  carbon  deposits  in  the  cylinder  will 
necessitate  frequent  cleaning  of  the  cylinder  walls,  piston  and 
rings. 

Some  engines  work  very  successfully  with  kerosene  and  the 
heavier  distillates,  if  the  fuel  is  vaporized  by  the  heat  secured  from 


GAS  AND  OIL  ENGINES  87 

exhaust  gases  in  a  coil  located  entirely  outside  the  engine  cyl- 
inder. It  has  been  found  that  the  injection  of  water  with  the 
fuel  reduces  the  carbon  deposits  in  the  cylinder  and  improves  the 
operation  of  the  engine.  Water  injection  increases  the  capacity 
of  an  oil  engine  when  operating  with  the  heavier  petroleum  fuels, 
but  decreases  the  economy.  The  supply  of  injection  water 
should  be  cut  off  at  light  loads  and  used  at  heavy  loads  in 
amounts  sufficient  to  prevent  preignition.  Preignition  is  indi- 
cated by  a  metallic  knock  within  the  cylinder. 

Oil  engines  for  burning  petroleum  fuels  heavier  than  35°Be*. 
have  been  perfected.  These  engines  are  either  of  the  Diesel  or 
semi-Diesel  types,  and  ignite  the  fuel  automatically.  The  prin- 
ciple of  construction  of  engines  for  heavy  fuels  will  be  explained 
in  the  section  on  "  ignition. " 

Cooling  of  Gas-engine  Cylinder  Walls. — The  necessity  for 
cooling  gas-engine  cylinder  walls  was  explained  in  an  earlier  part 
of  this  chapter.  In  smaller  engines  only  the  cylinder  or  cylinder 
and  cylinder  head  must  be  cooled.  In  large  engines  it  becomes 
necessary  to  cool  also  the  piston  and  exhaust  valve. 

Three  methods  are  used  for  cooling  gas  engines: 

1.  Air-cooling. 

2.  Water-cooling. 

3.  Oil-cooling. 

An  air-cooled  gasoline  engine  is  illustrated  in  Figs.  83  and  84. 
The  cylinder  is  cast  with  webs,  and  air  is  circulated  by  means  of 
a  fan  driven  from  the  engine.  In  very  small  engines  natural  air 
circulation  is  used.  The  air-cooling  system  has  not  been  found 
practical  for  stationary  engines  above  5  hp.  Even  for  small, 
engines  there  is  no  positive  temperature  control  with  this  system 
of  cooling.  This  often  results  in  the  decomposition  of  the  cylinder 
oil  and  in  carbon  deposits  on  the  piston  and  cylinder  walls. 

Cooling  of  cylinder  walls  by  means  of  water  is  the  most  com- 
mon method.  In  this  case  the  cylinder  barrel  or  the  cylinder 
barrel  and  cylinder  head  are  jacketed;  that  is,  they  are  built  with 
double  walls  and  water  is  circulated  through  the  space  between 
the  walls.  One  method  of  water-cooling  was  illustrated  in  con- 
nection with  the  hopper-cooled  engine  in  Fig.  72.  In  this  case 
the  water  is  heated  by  contact  with  the  hot  cylinder  walls,  rises 
and  is  replaced  by  cooler  water. 


88 


FARM  MOTORS 


Another  system  of  water-cooling  is  to  place  a  galvanized- 
iron  tank  filled  with  water  near  the  engine  and  connect  the  lower 
part  of  the  cylinder  jacket  to  the  bottom  of  the  tank  and  the 
upper  part  of  the  jacket  at  the  top  of  the  tank  (Fig.  85).  The 
cold  water  enters  the  jacket  at  the  bottom,  is  heated,  rises  and 


FIG.  83. — Air-cooled  cylinder. 

flows  to  the  upper  part  of  the  tank,  the  water  circulation  being 
similar  to  that  of  the  hopper-cooled  engine. 

In  order  to  definitely  control  the  temperature  of  the  water 
jacket,  the  forced  system  of  water  circulation  shown  in  Fig.  71 
is  preferable  to  the  two  described.  This  system  is  used  when  a 
constant  source  of  water  supply  is  available.  The  temperature 
in  the  jacket  is  usually  maintained  at  about  150°, 


GAS  AND  OIL  ENGINES 


89 


FIG.  84. — Air-cooled  engine. 


Y///W/W///////////^^^ 

FIG.  85. — Gas-engine  water-cooling  system. 


90 


FARM  MOTORS 


Another  method  of  water-cooling  by  forced  circulation,  used 
quite  extensively  on  small  stationary  and  portable  engines,  is 
illustrated  in  Fig.  86.  The  water  from  the  lower  part  of  the  tank 
T  is  forced  by  a  pump  through  the  jacket.  The  water  enters  the 
bottom  of  the  jacket,  and  leaves  from  the  top  of  the  jacket  by  the 
pipe  P.  The  water  is  then  allowed  to  pass  over  the  screen  S 
and  is  cooled  by  evaporation  before  reentering  the  tank.  The 
advantage  of  this  system  is  that  the  screen  acts  as  a  cooling  tower 


Fia.  86. — Gas-engine  water-cooling  system. 

and  reduces  the  weight  of  water  which  must  be  carried  with  the 
engine. 

Automobiles  and  traction  engines  are  provided  with  a  cel- 
lular or  tubular  radiator  for  cooling  the  water  from  the  cylinder 
jackets.  The  heated  water  passes  through  the  radiator,  where 
the  rush  of  air  to  which  it  is  exposed  absorbs  a  portion  of  the  heat 
and  cools  the  water.  A  fan  is  arranged  for  inducing  a  cold 
current  of  air  through  the  radiator. 

Oil  is  being  used  for  cooling  gas-engine  cylinders  to  a  limited 
extent  where  the  engines  are  exposed  to  low  temperatures.  The 
systems  of  oil-cooling  are  similar  to  water-cooling.  In  some 
cases  natural  circulation  is  employed,  using  hoppers  or  tanks, 
while  in  other  types  some  form  of  forced  cooling  like  the  one 
illustrated  in  Fig.  71  is  used.  However,  oil  is  not  a  satisfactory 


GAS  AND  OIL  ENGINES  91 

cooling  medium  on  account  of  its  inability  to  take  up  heat  as 
easily  as  water. 

In  some  cases  non-freezing  mixtures  composed  of  water,  alcohol 
and  glycerine  have  been  used  for  cooling  the  cylinders  of  gas  engines. 
Calcium  chloride  and  common  salt  solutions  have  also  been  used  to 
some  extent  for  the  cooling  of  engines.  These  mixtures  will  tend 
to  prevent  freezing  and  the  consequent  cracking  of  the  jacket  and 
cylinder  walls  during  cold  weather  when  the  engine  is  not  running. 

When  water  is  the  cooling  medium,  the  engine  should  be  pro- 
vided with  a  drain  cock  at  the  lowest  point  of  the  jacket,  so 
that  the  jacket  can  be  thoroughly  drained  in  freezing  weather. 

Gas-engine  Ignition  Systems. — Ignition  in  all  modern  gas 
engines  is  accomplished  either  by  an  electric  spark,  or  automat- 
ically by  the  high  compression  to  which  either  the  air  or  the  mix- 
ture is  subjected  in  the  engine  cylinder. 

In  some  older  makes  of  engines  the  hot-tube  system  of  ignition 
is  still  employed,  in  which  a  tube,  made  of  porcelain  or  of  some 
nickel  alloy,  is  open  at  one  end  to  the  cylinder  and  is  closed  at 
the  other.  The  closed  end  of  the  tube  is  heated  by  a  Bunsen 
burner.  A  portion  of  the  explosive  mixture  is  forced  into  the  tube 
during  the  compression  stroke  of  the  piston,  and  is  fired  by  the 
heat  of  the  tube  walls.  Accurate  timing  of  the  point  of  ignition 
is  quite  impossible  with  the  hot-tube  system.  The  only  points 
in  favor  of  this  system  are  the  low  first  cost  and  cost  of  main- 
tenance as  compared  with  the  electric  system. 

Electric  Ignition  Systems  for  Gas  Engines. — Electric  ignition 
for  farm  gas  and  oil  engines  has  practically  superseded  every 
other  form.  . 

Electric  ignition  is  produced  by  an  electric  spark  or  arc. 

In  one  system  the  spark  is  similar  to  that  produced  when  an 
electric  circuit  is  broken  by  the  opening  of  a  switch,  or  when  a 
wire  connected  to  one  pole  of  a  battery  is  drawn  across  the  other 
pole.  This  method  is  called  the  make-and-break  system  of 
ignition  and  is  produced  by  contact  and  then  quickly  separating 
metallic  points  which  are  located  within  the  clearance  space  of  an 
engine  cylinder. 

In  another  system  of  electric  ignition  a  current  of  high  voltage 
(electrical  pressure)  is  used  which  jumps  across  a  small  air  gap. 
This  system  is  called  the  jump-spark  ignition  system. 


FARM  MOTORS 


The  electric  current  for  producing  the  spark  in  the  make-and- 
break  system  is  usually  obtained,  from  a  primary  battery  of  dry 
cells  or  of  wet  cells,  from  a  storage  battery,  from  a  small  low- 
voltage  dynamo,  or  from  a  low-tension  magneto.  The  electric 
pressure  required  is  about  6  volts  and  can  be  produced  by  a 
battery  of  four  to  eight  dry  cells  in  series  or  by  a  storage  battery 
of  three  or  four  cells  in  series. 

The  source  of  current  for  the  jump-spark  system  may  be,  a 
battery  of  dry  or  of  wet  cells,  a  storage  battery  or  a  small  dynamo. 

Some  form  of  magneto,  as  will  be  ex- 
I  plained  later,  is  often  employed  for 

this  system  of  ignition. 

Those  not  familiar  with  the  funda- 
mentals of  electricity  should  study 
Chapter  X  before  taking  up  electric 
ignition. 

The  Make-and-break  System  of 
Ignition. — The  principle  of  the  make- 
and-break  system  is  illustrated  in  Fig. 
87.  B  is  a  battery  which  supplies  the 
electric  current  for  ignition.  C  is  an 
inductive  spark  coil,  often  called  a 
kick  coil.  It  consists  of  a  bundle  of  small  soft  iron  wires,  called 
the  core,  surrounded  by  a  coil  of  many  turns  of  insulated  copper 
wire  through  which  the  current  passes.  On  account  of  the  in- 
ductive action  of  such  a  coil,  the  spark  is  greatly  intensified, 
producing  a  strong  arc  with  a  small  current  from  a  battery  of 
low  voltage.  S  is  a  stationary  electrode  well-insulated  from  the 
engine  and  M  is  a  movable  electrode  not  insulated  from  the 
engine.  Both  electrodes  are  set  in  the  combustion  space  of  the 
cylinder.  The  contact  points  of  the  two  electrodes  are  brought 
together  by  means  of  a  cam  T  operated  from  the  valve  gear 
shaft  of  the  engine.  When  the  switch  W  is  closed,  current  will 
flow  through  the  circuit  as  soon  as  the  contact  points  of  the 
electrodes  are  brought  together  by  the  cam  T.  A  sudden  break- 
ing of  the  contact,  aided  by  a  spring,  causes  a  spark  to  pass  between 
the  points,  which  ignites  the  mixture.  The  more  rapidly  the 
electrodes  are  separated  the  better  is  the  spark  produced. 
The  contact  between  the  two  electrodes  of  the  make-and-break 


FIG. 


87. — Make-and-break 
ignition  system. 


GAS  AND  OIL  ENGINES 


93 


system  can  be  made  by  sliding  one  contact  point  over  the  other, 
this  being  known  as  the  wipe-spark  igniter  and  is  illustrated  in 
Fig.  88.  A  is  the  movable  and  B  is  the  stationary  electrode. 


FIG.  88. — Wipe-spark  igniter. 

Another  type,  shown  in  Fig.  89,  is  called  the  hammer-break 
igniter.     S  is  the  stationary  and  M  is  the  movable  electrode. 


FIG.  89. — Hammer-break  igniter. 

The  interrupter  lever  /  is  operated  from  a  cam  on  the  valve  gear 
shaft  until  the  two  contact  points  M  and  S,  which  are  located  in 
the  combustion  space  of  the  cylinder,  are  brought  into  contact. 
At  the  desired  time,  /  is  tripped  and  flies  back,  instantly  break- 


94  FARM  MOTORS 

ing  the  contact  and  producing  an  arc  between  M  and  /§».  Another 
form  of  hammer  make-and-break  igniter  is  illustrated  in  Fig.  90, 
the  contact  points  of  which  are  designated  M  and  S. 

Wipe-spark  igniters  (Fig.  88)  keep  the  contact  points  cleaner 
than  hammer-break  types  (Figs.  89  and  90).  The  hammer- 
break  igniter  is  more  commonly  used  on  account  of  the  easier 
adjustment  and  less  wear  of  the  contact  points. 

To  determine  the  point  of  ignition  with  the  make-and-break 
system,  the  engine  flywheel  is  turned  over  slowly  until  the  igniter 
snaps.  This  is  the  point  of  ignition  and  should  be  marked  on 
the  flywheel  and  frame  or  on  the  piston  and  cylinder,  so  that 
the  correct  timing  may  be  checked  at  any  time. 


FIG.  90. — Hammer-break  igniter. 

To  secure  best  results,  the  points*  of  the  igniter  must  be  clean 
and  free  from  carbon  and  corrosion,  all  connections  must  be 
tight,  and  the  wires  used  for  connecting  electrodes  with  source 
of  electricity  must  be  of  sufficient  size  to  allow  the  current  to 
flow  freely. 

The  size  of  the  inductance  coil  to  be  used  in  the  make-and-break 
system  depends  upon  the  speed  of  the  engine.  For  a  high-speed 
engine,  a  short  inductance  coil  should  be  employed,  as  the 
shorter  the  coil  the  quicker  is  the  magnet  brought  to  a  saturated 
state.  In  the  case  of  slow-speed  engines,  a  larger  coil  can  be 
used. 

The  Jump -spark  System  of  Ignition. — The  principle  of  the 
jump-spark  system  is  illustrated  in  Fig.  91.  A  is  a  spark  plug, 
the  spark  points  E  and  F  of  which  project  into  the  cylinder. 
These  spark  points  are  stationary,  insulated  from  each  other, 
and  separated  by  an  air  gap  of  about  J<}2  in-  When  the  switch 
W  is  closed,  the  current  from  the  battery  B  flows  through  the 


GAS  AND  OIL  ENGINES 


95 


timer  T,  which  completes  the  circuit  at  the  proper  time  through 
the  induction  coil  I,  and  the  induced  high- voltage  current  pro- 
duces a  spark  at  the  spark-plug  gap,  igniting  the  explosive  mix- 
ture in  the  cylinder. 

The  induction  coil  7,  Fig.  91,  differs  from  the  inductance  coil 
used  in  connection  with  the  make-and-break  system  of  ignition, 
in  that  two  layers  of  insulated  wire  are  wound  on  the  core  C  of 
the  induction  coil  and  only  one  layer  in  the  case  of  an  inductance 
coil.  In  an  induction  coil,  one  of  the  layers,  called  the  primary 
Pj  consists  of  several  turns  of  fairly  large  insulated  copper  wire. 
The  other  winding,  the  secondary 
S}  consists  of  many  turns  of  very 
fine  insulated  wire.  The  second- 
ary is  wound  over  the  primary 
winding,  but  has  no  metallic 
contact  with  the  primary.  The 
current  from  the  battery  B  enters 
the  primary  winding  P  of  the  in- 
duction coil  and  induces  a  high- 
voltage  current  in  the  secondary 
winding  S. 

R  is  the  vibrator,  sometimes 
called  a  trembler  or  an  interrupter. 
The  function  of  the  vibrator  R  is 
to  interrupt  the  primary  circuit 


FIG.  91. — Jump-spark  ignition 
system. 


with  great  rapidity;  this  action  induces  an  alternating  current 
in  the  secondary  and  a  series  of  sparks  at  the  air  gap  of  the 
spark  plug.  In  some  types  of  induction  coils,  the  vibrator  is 
omitted  and  but  one  spark  is  produced  at  the  spark  plug. 

K  is  known  as  an  electric  condenser.  The  condenser  consists 
of  alternate  layers  of  tin  foil  and  insulating  material  like  paraffined 
paper.  The  condenser  acts  like  an  air  chamber  of  a  pump,  in 
that  it  absorbs  the  excess  of  current  at  the  primary  winding, 
prevents  sparking  at  the  vibrator,  and  gives  out  this  excess  at 
the  proper  time  to  increase  the  intensity  of  the  spark. 

The  condenser  as  well  as  the  windings  and  the  core  of  an  in- 
duction coil  are  placed  in  a  box  made  of  wood,  and  the  space 
between  the  parts  is  filled  with  an  insulating  material,  usually 
paraffin  or  some  similar  wax  mixture,  in  order  to  protect  the 


96  FARM  MOTORS 

parts  from  moisture.  A  complete  induction  coil  for  a  jump- 
spark  system  is  shown  in  Fig.  92.  Induction  coils  operate  on 
about  6  volts. 

Fig.  93  shows  inductance  coils  suitable  for  make-and-break 
systems  of  ignition. 


FIG.  92. — Induction  coil.  FIG.  93. — Inductance  coils. 

In  automobile  practice,  where  four  or  more  cylinders  are  used, 
induction  coils  are  made  up  in  units,  each  unit  supplying  a  spark 
to  one  cylinder.  In  some  cases  each  coil  has  its  own  vibrator; 
in  other  types  one  vibrator,  called  a  master  vibrator, 
is  so  connected  that  it  breaks  the  current  for  each 
induction  coil  in  turn.  The  s'ystem  with  a  master 
vibrator  produces  better  timing  of  ignition,  but  an 
accident  to  the  master  vibrator  interrupts  the  entire 
•  system. 

A  spark  plug  used  in  connection  with  the  jump- 
spark  system  of  ignition  is  illustrated  in  Fig.  94. 
It    consists    essentially    of    two    metallic    points, 
well-insulated  from  each  other.     The  central  point 
is  connected  to  the  binding   post   which  receives 
current  from  the  secondary,  or  high-tension  wind- 
FIG.  94. —     ing  of  the  induction  coil.     The  other  point  is  not 
park  plug.    jnsu]ate(j  from  faQ  thread,  and  completes  the  circuit 
when  the  spark  plug  is  in  the  engine  cylinder. 

Comparing  the  two  systems  of  electric  ignition,  the  jump-spark 
system  is  much  more  simple  mechanically  as  it  has  no  moving 
parts  inside  the  cylinder.  The  make-and-break  system  is  simpler 
electrically,  requires  less  care  in  wiring,  does  not  have  to  be  in- 
sulated so  carefully  and  the  spark  is  more  certain.  It  is  difficult 
to  lubricate  the  many  mechanical  parts  of  the  make-and-break 
system.  The  make-and-break  system  is  usually  used  on  station- 
ary slow-speed  engines  and  to  some  extent  on  traction  engines. 


GAS  AND  OIL  ENGINES  97 

The  jump-spark  system  is  better  adapted  for  high-speed  and 
multiple-cylinder  engines  than  is  the  make-and-break,  and  is 
used  on  automobiles,  small  stationary  engines,  marine  engines 
and  also  on  traction  engines. 

Ignition  Dynamos. — An  ignition  dynamo  is  a  miniature  direct- 
current  electric  generator,  built  on  the  same  plan  as  any  large  dy- 
namo used  for  lighting  (see  Chapter  X) .  It  has  electromagnets  as 
field  magnets  and  is  usually  of  the  iron-clad  type.  One  form  of 
ignition  dynamo  is  shown  in  Fig.  95.  In  using  an  ignition 
dynamo  the  internal-combustion  engine  must  be  started  on 
batteries,  as  the  speed  developed  when  turning  the  engine  by 
hand  is  insufficient  to  produce  a  spark  of  sufficient  intensity  by 
the  dynamo.  As  soon  as  the  engine  speeds  up,  the  battery 
current  is  thrown  off  and  the  spark  is  supplied  by  the  ignition 
dynamo.  Most  ignition  dynamos  will  supply  a  spark  of  sufficient 
intensity  for  a* make-and-break  system  of  ignition  without  an 
inductance  coil.  A  5-volt  and  3-  to  5-amp.  generator  is  suitable 
for  make-and-break  ignition.  For  jump-spark  ignition  a  special 
induction  coil  must  be  used  with  the  ignition  dynamo. 

Magnetos. — The  magneto  differs  from  the  ignition  dynamo 
in  that  its  magnetic  fields  are  permanent  magnets.  For  this 
reason  it  is  unnecessary  to  run  the  magneto  for  any  length  of  time 
in  order  to  build  up  its  field.  Magnetos  can  be  operated  in 
either  direction  and  at  any  speed.  Magnetos  may  be  classed 
under  two  heads: 

1.  High-tension  magnetos  which  generate  sufficient  voltage  to 
jump  the  gap  of  a  spark  plug. 

2.  Low-tension  magnetos  which  include  all  other  types  and 
are  used  in  place  of  batteries  or  of  batteries  and  inductance 
coil. 

Low-tension  Magnetos. — The  low-tension  magneto,  shown  in 
Fig.  96,  is  of  the  direct-current  type  and  differs  from  the  ignition 
dynamo  (Fig.  95)  in  that  the  magneto  field  is  a  permanent  mag- 
net. This  type  of  low-tension  magneto  can  be  used  for  charging 
a  storage  battery  or  for  producing  illumination  on  a  very  small 
scale.  The  direct  current  from  the  magneto  (Fig.  96)  is  taken 
off  by  two  brushes  which  press  on  the  opposite  sides  of  a  com- 
mutator. This  type  of  magneto  is  usually  driven  by  a  friction 
wheel  or  by  a  belt,  and  must  be  operated  at  high  speeds. 


98 


FARM  MOTORS 


Fig.  97  illustrates  a  low-tension  alternating-current  magneto. 
This  type  of  magneto  generates  an  alternating  current  of  high 
frequency  and  can  be  used  in  connection  with  a  vibrating  in- 


FIG.  95. — Ignition  dynamo. 

duction  coil  for  jump-spark  ignition  systems.     It  is  not  neces- 
sary that  this  type  of  magneto  be  timed  with  the  engine. 


FIG.  96. — Low-tension  direct- 
current  magneto. 


FIG.  97. — Low-tension  alternat- 
ing-current magneto. 


The  low-tension  magneto  (Fig.  98)  also  generates  an  alternat- 
ing current,  but  differs  from  the  low-tension  magneto  of  Fig.  97 
in  that  the  alternating  current  is  of  low  frequency.  This  type  of 


GAS  AND  OIL  ENGINES 


99 


magneto  is  used  mainly  for  the  make-and-break  system  of  igni- 
tion and  takes  the  place  of  batteries  and  induction  coil.  The 
magneto  of  the  type  shown  in  Fig.  98  must  be  timed  with  the 


FIG.       98. — Low-tension        FIG.  99. — Magneto  with  circuit-breaker 
low-frequency  magneto.  and  distributor. 


FIG.  100. — Oscillating  magneto. 

engine,  as  the  current  is  produced  only  for  a  small  portion  of  a 
revolution. 

The  magneto  illustrated  in  Fig.  99  is  also  a  low-tension  alter- 
nating-current low-frequency  magneto,  but  is  equipped  with  a 


100 


FARM  MOTORS 


circuit-breaker  anpl  distributor  so  that  this  form  can  be  used  for 
jump-spark  system  when  connected  with  a  non- vibrating  induc- 
tion coil.  This  type  of  low-tension  magneto  is  often  used  in 
connection  with  the  "dual  system;"  that  is,  with  batteries  for 
starting  and  magneto  for  operating. 

Low-tension  magnetos  are  sometimes  built  in  the  form  of  an 
oscillating  magneto  (Fig.  100).     The  oscillating  magneto  pro- 


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duces  a  spark  irrespective  of  the' speed  of  the  engine,  which  is  an 
advantage  in  starting.  This  form  of  magneto  is  usually  of  the 
alternating-current  low-frequency  type  and  is  best-adapted  for 
slow-speed  single-cylinder  engines. 

High-tension  Magnetos. — A  high-tension  magneto  is  shown  in 
Fig.  101.     This  type  of  magneto  is  used  for  the  jump-spark 


GAS  AND\OrL>MH$        .  101 

ignition  systems  and  differs  from  the  low-tension  magnetos,  in 
that  the  high-tension  magneto  can  generate  a  high-voltage  cur- 
rent without  the  aid  of  an  induction  coil.  The  armature  of  the 
high-tension  magneto  is  provided  with  two  windings,  a  primary 
and  a  secondary,  carries  a  condenser  and  has  a  circuit-breaker 
at  one  end. 

The  high-tension  magneto  is  provided  with  a  distributor  if  it 
serves  an  engine  with  several  cylinders.  In  traction  engines 
and  other  large  engines,  the  high-tension  magneto  is  usually 
equipped  with  "impulse  starters,"  which  give  intermittent 


Fia.  102.— Timer. 

rotation  to  the  armature  or  to  the  rotating  element  of  the  magneto 
until  the  engine  has  attained  a  definite  speed,  after  which  time 
the  magneto  operates  at  constant  speed. 

Timers. — The  function  of  a  timer  is  to  control  the  flow  of  the 
low- voltage  current  as  it  comes  from  the  battery  or  magneto,  by 
closing  the  primary  circuit  of  the  jump-spark  system  at  the  proper 
time.  The  timer  consists  of  one  stationary  and  of  one  rotating  part. 
Both  parts  are  insulated  electrically  from  each  other.  One  part 
is  constructed  of  some  insulating  material,  such  as  rubber  or 
wood  fiber,  and  has  pieces  of  metal,  called  segments,  set  at  defi- 


102 


MOTORS 


nite  distances  apart,  according  to  the  number  of  cylinders  and 
number  of  induction  coils  used.  As  the  rotating  part  revolves, 
it  comes  into  contact  with  these  metal  segments,  completing  the 

circuit.  If  a  four-cylinder  engine 
has  induction  coils  for  each  one 
of  the  cylinders  there  is  a  metallic 
contact  piece  on  the  stationary 
part  for  each  cylinder. 

Two  forms  of  timers  are  illu- 
strated in  Figs.  102  and  103.  S 
is  the  stationary  part  of  the 


timer,  R  is  the  revolving  part, 
and  E  reprsents  the  segments 
which  make  contact  as  the  timer 
revolves. 


FIG.  103.— Timer. 


FIG.  104. — Circuit  breaker.  . 


In  automobiles,  the  timer  is  connected  to  the  spark  lever  on 
the  steering  wheel  (Chapter  VI). 


PIG.  105. — Wiring  diagram,  battery  and  magneto  ignition. 

Fig.  104  shows  the  construction  of  a  circuit-breaker  or  inter- 
rupter. This  form  of  timer  is  used  in  connection  with  high- 
tension  magnetos  or  with  a  low-tension  magneto  and  induction 
coil. 


GAS  AND  OIL  ENGINES 


103 


Fig.  105  shows  a  wiring  diagram  for  a  single-cylinder  engine, 
with  battery  and  magneto  ignition. 

Automatic  Ignition  for  Oil  Engines. — One  type  of  oil  engine, 
the  Hornsby  Akroyd,  is  illustrated  in  Fig.  106.  The  engine  is 
provided  with  an  unjacketed  vaporizer  A,  which  communicates 
with  the  cylinder  by  means  of  the  small  opening  B.  This  vapor- 
izer is  raised  to  a  red  heat  before  starting,  by  means  of  a  torch, 
and  is  kept  hot  by  repeated  explosions  when  the  engine  is  running. 
This  engine  works  on  the  regular  four-stroke '  Otto  gas-engine 
cycle.  During  the  suction  stroke  of  the  piston  only  air  is  sucked 


FIG.  106. — Hot-bulb  oil  engine. 

into  the  cylinder  and  the  charge  of  oil  fuel  is  injected  into  the 
vaporizer  by  a  pump.  On  the  return  stroke  the  air  is  compressed, 
forced  in  the  vaporizer,  mixed -with  the  fuel  and  automatically 
ignited.  This  is  followed  by  the  expansion  and  exhaust  strokes, 
as  in  other  internal-combustion  engines. 

A  modification  of  this  type  of  engine  is  the  so-called  semi- 
Diesel  type  of  oil  engine,  which  is  well-adapted  for  the  burning 
of  the  lowest  grades  of  petroleum  fuels.  In  this  case  the  air  is 
compressed  to  about  250  Ib.  per  square  inch  before  the  fuel  is 
injected  into  the  cylinder. 

The  Diesel  engine  was  mentioned  in  the  first  part  of  this  chap- 


104 


FARM  MOTORS 


ter.  It  is  very  economical  for  the  burning  of  low  grades  of  fuel, 
but  the  high  first  cost  of  the  engine  limits  its  field  of  application 
in  small  sizes. 

Lubrication  of  Gas  and  Oil  Engines. — The  selection  of  the 
proper  lubricating  oils  and  of  the  best  oiling  devices  is  of  great 
importance,  if  reliability  of  operation  and  long  life  of  an  internal- 
combustion  engine  are  desired. 

The  extremely  high  temperatures  which  are  developed  within 
the  cylinder  of  a  gas  engine  or  of  an  oil  engine  and  the  absence  of 
moisture  make  the  selection  of  the  proper  oil  a  necessity.  Oils 
employed  for  lubricating  steam-engine  cylinders  are  not  suitable 


FIG.  107. — Sight-feed  gas-engine  oiler. 

for  internal-combustion  engines.  Such  petroleum  lubricating 
oils  should  be  employed  as  are  light,  are  fairly  thin,  will  with- 
stand high  temperatures,  are  free  from  acid  and  from  animal  or 
vegetable  matter  and  which  will  leave  no  carbon  deposits.  The 
lubricating  oil  should  flow  freely  at  all  seasons  of  the  year  and 
should  not  easily  vaporize  at  the  high  temperatures. 

Oil  which  will  gum  or  form  carbon  deposits  will  tend  to  make 
the  piston  rings  stick  or  may  produce  preignition. 

Graphite  is  satisfactory  for  lubricating  certain  parts  of  an 
internal-combustion  engine  outside  the  cylinder.  In  general, 
the  gas-engine  oil  used  for  lubricating  the  engine  cylinder  will  be 


GAS  AND  OIL  ENGINES 


105 


found  satisfactory  for  bearings  and  other  parts,  but  in  large 
engines  a  saving  can  be  produced  by  employing  a  cheaper  oil 
for  the  bearings. 

Single-cylinder  gas  and  oil  engines  are  usually  lubricated  by  a 
sight-feed  oiler  (Fig.  107). 
This  oiler  differs  from  the 
ordinary  sight-feed  oiler  in 
that  a  check  ball  (U)  is  used 
in  order  to  guard  the  oiler 
during  a  portion  of  the  cycle 
from  the  pressure  within  the 
cylinder. 

The  mechanical  oiler  (Fig. 


FIG.  108. — Mechanical  oiler. 


108)  holds  a  large  quantity  of 

oil,  is  positive  in  action  and 

requires  little  care.     In  high-speed  motors,  the  forced-flooded 

system  of  lubrication  is  commonly  employed  (Fig.  109).     In  this 


FIG.  109. — Forced-flooded  lubrication  system. 

system  a  pump  forces  oil  to  the  various  bearings,  keeping  them 
flooded  with  oil  at  all  times. 

The  splash  system  of  oiling  is  usually  more  satisfactory  with 


106  FARM  MOTORS 

gasoline  engines  than  with  kerosene  engines,  as  the  kerosene 
which  gets  by  the  piston  is  injurious  to  the  lubricating  properties 
of  the  oil  in  the  crank  case. 

Governing  of  Gas  Engines. — Every  gas  engine  must  be  pro- 
vided with  some  governing  mechanism  in  order  that  its  speed 
may  be  kept  constant  as  the  power  developed  by  the  engine 
varies.  The  governing  mechanism  is  operated  by  the  speed 
variations  of  the  engine  and  the  speed  control  is  accomplished 
by  the  following  methods. 

1.  Hit-or-miss  Governing. — In  this  system  the  number  of 
explosions  is  varied  according  to  the  load  on  the  engine.  This 
can  be  carried  out  in  several  ways,  depending  on  the  valve  gear 
of  the  engine. 

In  the  case  of  small  engines,  where  the  inlet  valve  is  auto- 
matically operated  by  the  vacuum  created  in  the  cylinder  during 
the  suction  stroke,  the  governor  operates  on  the  exhaust  valve 
by  holding  it  open  during  the  suction  stroke.  The  free  communi- 
cation of  the  engine  cylinder  with  the  outside  prevents  the  forma- 
tion of  sufficient  vacuum  in  the  cylinder  to  lift  the  inlet  valve. 

When  the  inlet  valve  is  mechanically  operated  from  the  valve 
gear  shaft,  the  governor  acts  on  the  inlet  valve,  keeping  it  closed 
part  of  the  time  at  light  loads.  The  governor  used  to  accomplish 
this  is  usually  some  form  of  flyball  governor.  As  the  speed  of 
the  engine  increases,  the  balls  are  thrown  out  by  centrifugal 
force  and  shift  the  position  of  a  cam  on  the  valve  gear  shaft,  pre- 
venting the  opening  of  the  inlet  valve. 

The  hit-or-miss  system  of  governing  can  also  be  carried  out  by 
having  the  governor  open  a  switch,  thus  interrupting  the  flow 
of  current  to  the  igniter,  as  the  load  decreases.  This  method  is 
very  wasteful  of  fuel  as  the  fuel  drawn  in  at  each  suction  stroke 
passes  through  the  engine  and  is  wasted.  It  should  be  used 
only  in  connection  with  one  of  the  other  methods  of  governing. 

The  hit-or-miss  system  of  governing  is  very  simple  and  gives 
good  fuel  economy  at  variable  loads.  As  the  explosions  in  the 
engine  do  not  occur  at  regular  intervals,  this  system  of  governing 
necessitates  the  use  of  very  heavy  flywheels  in  order  to  keep  the 
speed  fluctuations  within  practical  limits.  The  hit-or-miss 
system  is  very  well-adapted  for  small  and  also  for  medium-sized 
engines  where  very  close  speed  regulation  is  not  essential. 


GAS  AND  OIL  ENGINES 


107 


2.  Varying  Quantity  of  Mixture. — In  this  system  the  propor- 
tion of  air  to  fuel  is  kept  constant  and  the  quantity  of  the  mix- 
ture admitted  into  the  cylinder  is  varied  according  to  the  load. 
This  variation  is  accomplished  either  by  throttling  the  charge  or 
by  changing  the  time  during  which  the  inlet  valve  is  open  to  the 
cylinder.  In  fact,  the  two  methods  of  varying  the  quantity  of 


FIG.  110.— Silo  filling. 

the  mixture  are  similar  to  those  used  in  governing  steam  engines 
and  as  explained  in  Chapter  IV. 

3.  Varying  Quality  of  Mixture. — In  this  case  the  total  quantity 
admitted  into  the  cylinder  is  kept  constant,  but  the  amount  of 
fuel  mixed  with  the  air  is  varied  according  to  the  load. 

When  gas  engines  are  governed  by  varying  the  quantity  or 
quality  of  the  mixture,  the  speed  is  more  uniform  at  variable 
loads.  Also,  since  the  explosions  occur  at  definite  periods,  the 


108 


FARM  MOTORS 


temperatures  inside  the  cylinder  are  kept  more  constant.  The 
throttling  form  of  governor  is  used  most  commonly  with  trac- 
tion engines. 


FIG.   111. — Gasoline-engine  and  sheller  mounting. 


FIG.  112. — Engine  driving  a  hay  press. 

The  Gasoline  Engine  on  the  Farm. — Some  of  the  uses  to  which 
a  gasoline  engine  can  be  applied  on  the  farm  are  illustrated  in 
Figs.  110  to  117. 


GAS  AND  OIL  ENGINES 


109 


A  12-hp.  gasoline  engine  is  used  for  silo  filling  in  Fig.  110. 
Fig.  Ill  illustrates  a  gasoline  engine  applied  to  shelling  corn. 


FIG,  113. — Engine  driving  binder. 


FIG.  114. — Spraying  outfit. 

A  7-hp.  engine  driving  a  hay  press  is  illustrated  in  Fig.  112. 

A  binder  driven  by  a  4-hp.  engine  is  shown  in  Fig.  113. 

An  air-cooled  gasoline  engine  of  2  hp.;  direct-connected  to  a 


110 


FARM  MOTORS 


FIG.  115. — Pumping  water. 


FIG.  116. — Driving  cream  separator, 


GAS  AND  OIL  ENGINES  111 

spraying  outfit  (Fig.  114),  is  capable  of  producing  a  pressure  of 
100  Ib.  per  square  inch  or  more,  as  compared  with  about  50  Ib. 
in  the  case  of  the  hand  sprayer. 

The  application  of  the  gasoline  engine  to  pumping  water  for 
farm  use  is  illustrated  in  Fig.  115. 

Fig.  116  shows  the  application  of  the  small  gasoline  engine  for 
the  driving  of  cream  separators. 

A  wood-sawing  rig,  Fig.  117,  can  be  removed  by  loosening 
clamp  bolts,  and  the  engine  used  for  grinding  feed,  pumping, 
shredding,  or  for  any  other  farm  work  within  its  capacity. 


FIG.  117. — Wood-sawing  rig. 

Other  uses  to  which  the  gasoline  engine  can  be  put  include: 
the  driving  of  cement  mixers  and  rock  crushers,  the  grinding  of 
feed,  the  driving  of  grindstones  and  other  tools  in  the  farm  shop, 
the  driving  of  electric  generators  for  farm  lighting  (see  Chapter 
X),  and  for  various  other  work  about  the  house,  barn  and  dairy 
which  require  power. 

Gas  tractors  and  their  field  of  application  will  be  taken  up  in 
Chapter  VII. 

SELECTION  AND  MANAGEMENT  OF  GAS  AND  OIL  ENGINES 

Selecting  a  Gas  Engine. — A  gas  engine  should  be  selected 
large  enough  to  do  the  required  work,  as  it  will  stand  but  little 
overload.  This  is  due  to  the  fact  that  the  gas  engine  develops 
its  maximum  power  when  a  full  charge  of  the  best  mixture  of 


112  FARM  MOTORS 

fuel  and  air,  at  the  maximum  density,  has  been  admitted  to  the 
engine  cylinder.  On  the  other  hand,  an  engine  too  large  for 
the  work  it  has  to  do  will  give  poor  fuel  economy. 

As  the  economy  is  very  nearly  independent  of  the  size  of  the 
gas  engine,  it  is  better  to  buy  two  small  engines  than  one  large 
one.  This  applies  especially  to  the  farm,  where  the  larger  engine 
of  6  to  10  hp.  can  be  used  for  the  heavier  work,  such  as  feed 
grinding,  threshing,  wood  sawing,  etc.,  and  a  small  engine  of 
about  2  hp.  for  the  many  small  tasks,  about  the  house,  dairy, 
and  barn,  which  require  but  little  power.  An  engine  of  2  hp. 
is  sufficient  to  drive  a  small  dynamo,  to  light  the  house,  barn,  etc., 
and  to  charge  a  storage  battery  (see  Chapter  X).  The  same 
engine,  if  portable,  can  be  used  for  driving  a  washing  machine  and 
wringer,  a  tree-sprayer  outfit,  a  house  pump,  a  cream  separator, 
etc. 

An  engine  governed  by  the  hit-or-miss  principle  should  carry 
such  a  load  as  will  enable  it  to  miss  one  explosion  in  every  eight, 
as  this  will  keep  the  cylinder  free  from  inert  burned  gases  and  will 
improve  the  economy.  If  an  engine  is  worked  at  its  maximum 
power  the  largest  part  of  the  time,  the  wear  on  the  parts  will  be 
too  great. 

An  engine  for  farm  use  must  be  capable  of  being  started 
easily  and  should  be  simple  in  construction.  Every  gas  engine 
must  have  certain  parts  to  carry  out  the  cycle  of  operations,  as 
explained  in  the  earlier  part  of  this  chapter,  but  some  engines 
are  provided  with  many  attachments,  which  have  good  points, 
but  which  complicate  the  engine  so  that  the  first  cost  is  greater 
and  the  manipulation  more  difficult.  An  engine  to  be  of  value  on 
the  farm  must  be  sufficiently  simple  in  construction  that  ordi- 
nary adjustments  and  repairs  can  be  made  without  the  aid  of 
experts. 

In  regard  to  the  method  of  igniting  the  mixture,  the  electric 
system  is  best  for  gasoline  engines.  It  is  well  to  provide  a  gaso- 
line engine  with  a  magneto  or  ignition  dynamo,  as  with  batteries 
the  cost  of  upkeep  is  considerable  and  the  reliability  of  opera- 
tion uncertain.  Regarding  drives  for  magnetos,  friction  and 
belt  drives  should  not  be  selected,  as  they  are  not  reliable.  A 
magneto  should  always  be  positively  driven  from  the  engine  by 
gears. 


GAS  AND  OIL  ENGINES  113 

There  is  very  little  choice  between  the  jump-spark  and  the 
make-and-break  systems  of  ignition.  For  stationary  engines 
the  make-and-break  is  commonly  used  while  the  jump-spark  is 
more  common  on  automobiles  and  traction  engines.  No  matter 
which  system  of  electric  ignition  is  selected,  the  various  wires 
should  be  well-insulated,  and  inclosed  in  some  moisture-proof 
conduit.  ,  - 

For  irrigation  work  where  the  cost  of  fuel  is  an  important  item, 
an  engine  should  be  selected  which  will  operate  with  the  cheaper 
fuels.  For  engines  under  100  hp.,  those  which  will  burn  kerosene 
or  solar  oil  will  usually  be  found  satisfactory.  Such  engines 
employ  electric  ignition  and  the  fuel  is  vaporized  in  a  coil  entirely 
outside  the  engine  cylinder.  For  work  requiring  100  hp.  and 
more  the  various  engines  with  automatic  ignition,  which  use  fuel 
oil,  will  be  found  more  economical. 

It  is  essential  to  select  an  engine  from  a  reputable  manufacturer. 
Every  engine  is  subject  to  breakage  of  parts  and  it  is  important 
that  duplicate  parts  may  be  easily  secured.  It  is  also  well  to 
investigate  the  work  done  by  engines  of  various  makes  before 
making  the  final  selection. 

The  rated  horsepower  of  an  engine  does  not  often  mean  the 
same  actual  power  for  different  makes  of  engines.  An  engine 
rated  at  10  hp.  by  one  manufacturer  may  be  capable  of  develop- 
ing 10  to  25  per  cent,  more  power  than  an  engine  of  the  same 
rating  by  another  manufacturer.  The  purchaser  should  insist 
on  a  definite  statement  as  to  the  actual  brake  horsepower  which 
the  engine  is  capable  of  developing.  The  method  of  obtaining 
the  brake  horsepower  of  an  engine  was  explained  in  Chapter  II. 

Installation  of  Gas  Engines. — It  is  usually  best  to  locate  a 
gas  engine  in  a  separate  room.  The  room  should  be  well-lighted 
and  ventilated,  free  from  dirt  and  dust  and  large  enough  so 
that  there  is  sufficient  space  for  easy  access  to  any  part  of  the 
engine  so  as  to  facilitate  starting,  oiling  and  inspection  of  all 
parts. 

In  connection  with  gasoline  and  oil  engines,  the  fuel  tank 
should  be  located  outside  the  building  and  preferably  under- 
ground. In  any  case  the  tank  must  be  lower  than  the  pipe  to 
which  it  is  connected  in  the  engine  room. 

As  the  mixture  of  fuel  and  air  is  ignited  inside  the  engine 
8 


114  FARM  MOTORS 

cylinder,  the  resulting  explosion  produces  a  shock  of  considerable 
magnitude  on  the  mechanism,  which  in  turn  is  transmitted  to 
the  foundation.  The  foundation  should  be  as  solid  as  possible. 
If  the  engine  is  to  be  set  on  a  wood  floor,  it  is  usually  well  to  lay 
long  timbers  on  or  under  the  floor  and  at  right  angles  to  the 
joists.  If  the  foundation  is  to  be  built  of  brick  or  of  concrete 
it  should  be  sufficiently  heavy  and  should  be  separated  from  the 
walls  of  the  building,  so  that  vibrations  caused  by  the  engine 
will  not  affect  the  building  or  surrounding  buildings.  If  the 
engine  has  to  be  located  over  another  room  it  is  best  to  place  the 
engine  in  a  corner  and  near  the  wall. 

The  method  of  constructing  foundations  for  steam  engines  was 
explained  in  detail  in  Chapter  IV.  The  directions  given  there 
apply  also  to  gas  engines. 

If  the  engine  is  to  be  connected  to  the  machines  to  be  driven 
by  belt  drive,  the  driver  and  the  driven  should  be  placed  far 
enough  apart,  that  the  required  power  can  be  transmitted  without 
running  the  belts  too  tight.  A  distance  between  pulleys  equal 
to  about  eight  times  the  size  of  the  larger  pulley  will  usually  give 
good  results.  Open  belts  are  preferable  to  crossed  belts  and 
should  be  used  whenever  possible. 

The  exhaust  piping  should  be  as  straight  and  as  short  as  pos- 
sible. The  exhaust  gases  should  always  be  discharged  out  of 
doors,  as  the  fumes  are  poisonous.  Some  engines  are  provided 
with  exhaust  mufflers  (Fig.  71)  which  can  be  located  near  the 
engine.  As  a  rule,  it  is  better  to  locate  the  muffler  outside  the 
building.  Engines  should  never  exhaust  into  a  flue  or  chimney. 

The  air  supply  can  be  taken  from  the  room  in  which  the  engine 
is  placed  or  from  the  outside.  In  all  cases  a  screen  should  be 
placed  over  the  air  pipe. 

Instructions  for  Operating  Gas  Engines. — Before  an  engine  is 
started  for  the  first  time,  all  the  working  parts  should  be  care- 
fully examined  and  nuts  and  other  fasteners  properly  tightened. 
The  electrical  connections  should  then  be  gone  over  and  the  spark 
plug  or  spark  points  removed  from  the  cylinder  and  tried. 

The  operation  and  economy  of  a  gas  engine  is  greatly  influenced 
by  the  proper  timing  of  the  valves  and  by  the  point  of  ignition. 

The  exhaust  valve  should  open  before  the  end  of  the  power 
stroke.  This  is  necessary  to  prevent  loss  of  power  when  the 


GAS  AND  OIL  ENGINES  115 

piston  starts  on  the  exhaust  stroke.  The  exhaust  valve  should 
begin  to  open  when  the  crank  is  at  an  angle  of  from  20°  to  40° 
before  the  outer  dead-center.  The  time  of  opening  of  the  exhaust 
valve  must  be  earlier  for  high-speed  than  for  slow-speed  engines. 

The  exhaust  valve  should  remain  open  until  the  crank  has 
turned  3°  to  8°  beyond  the  completion  of  the  exhaust  stroke. 

The  suction  stroke  follows  the  exhaust  stroke,  and,  in  order 
to  prevent  the  mixing  of  the  fresh  charge  with  the  burnt  gases, 
the  inlet  valve  should  open  about  3°  (crank  rotation)  after  the 
exhaust  valve  closes.  The  time  of  closing  of  the  inlet  valve  should 
be  after  the  crank  has  turned  10°  to  25°  beyond  the  completion 
of  the  suction  stroke. 

The  setting  of  the  gas-engine  valves  so  that  they  will  open  and 
close  at  the  proper  time,  can  be  accomplished  by  adjusting  the 
length  of  the  valve  push  rods  or  by  changing  the  timing  of  the 
cam  gears.  The  exact  setting  of  the  valves  will  depend  upon  the 
engine  speed,  and  upon  the  fuel  used. 

Ignition  should  be  timed  to  suit  the  fuel,  the  compression  and 
the  speed  of  the  engine. 

In  order  that  the  entire  mixture  may  be  ignited  and  burning  at 
the  beginning  of  the  power  stroke,  it  is  necessary  to  have  the 
spark  advanced;  that  is,  the  point  of  ignition  must  occur  earlier 
than  the  beginning  of  the  power  stroke. 

Proper  ignition  can  best  be  determined  by  an  indicator  (Fig.  1). 
The  experienced  operator  can  set  the  spark  very  nearly  at  the 
proper  place  by  the  sound  of  the  engine.  For  the  inexperienced 
operator  the  following  approximate  rules  should  prove  of  value : 

For  jump-spark  system,  turn  crank  and  set  spark  mechanism 
so  that  ignition  will  occur,  5°  ahead  of  dead-center,  for  every 
100  r.p.m.  of  the  engine  speed  rating. 

For  the  make-and-break  system,  advance  spark  approximately 
8°  for  every  100  revolutions  of  engine  speed  rating. 

As  an  illustration  of  the  application  of  the  above  rule,  calcu- 
late the  spark  advance  for  a  stationary  engine  operating  at 
350  r.p.m.  If  the  engine  has  make-and-break  ignition  system, 
ignition  should  take  place  when  the  crank  is  at  a  position  of  28° 
before  dead-center.  In  case  a  jump-spark  system  is  employed, 
the  spark  should  occur  when  the  crank  is  at  a  position  of  about 
before  dead-center. 


116  FARM  MOTORS 

The  gas  engine  is  not  self-starting,  as  is  the  steam  engine  when 
steam  is  turned  on.  The  reason  for  this  is  that  the  explosive 
mixture  of  fuel  and  air  must  be  taken  into  the  cylinder  and  com- 
pressed before  it  can  give  up  its  energy  by  explosion.  It  is, 
therefore,  necessary  to  set  the  engine  in  motion  by  some  external 
means  not  employed  in  regular  operation,  before  it  will  pick  up 
the  normal  working  cycle.  Engines  under  20  hp.  are  usually 
started  by  hand.  This  is  done  by  disconnecting  the  engine 
from  its  load  and  turning  the  flywheel  by  hand  for  a  few  revolu- 
tions. If  everything  is  in  good  condition  an  engine  should  start 
with  two  or  three  turns  of  the  flywheel  and  should  continue  to 
run  after  the  first  explosion.  An  easier  method  of  starting  gaso- 
line engines  is  to  set  the  engine  at  the  end  of  the  power  stroke,  in- 
ject some  gasoline  into  the  cylinder  through  a  priming  cock,  turn 
the  flywheel  backward  against  compression  as  far  as  possible  and 
then  quickly  trip  the  igniter. 

As  it  is  difficult  to  pull  over  an  engine  by  hand  against  com- 
pression throughout  the  whole  stroke,  some  engines  are  provided 
with  a  starting  cam,  which  can  be  shifted  so  as  to  engage  the 
exhaust  valve  lever.  This  relieves  the  compression  while  crank- 
ing, as  the  exhaust  port  is  open  during  the  first  part  of  the  com- 
pression stroke.  After  the  engine  speeds  up  the  starting  cam  is 
disengaged. 

Gas  engines  larger  than  25  hp.  are  usually  started  with  com- 
pressed air.  If  the  engine  consists  of  two  or  more  cylinders, 
this  can  be  accomplished  by  shutting  off  the  gas  supply  to  one 
of  the  cylinders  and  running  this  cylinder  with  compressed  air 
from  a  tank,  in  the  same  manner  as  a  steam  engine  is  operated 
with  steam  from  a  boiler.  As  soon  as  the  other  cylinders  pick 
up  their  cycle  of  operations  the  compressed  air  is  shut  off  and 
fuel  with  air  is  admitted  to  the  cylinder  used  in  starting.  With 
large  gas  engines  of  only  one  cylinder,  the  compressed  air  is  ad- 
mitted long  enough  to  start  the  engine  revolving,  when  the  com- 
pressed air  is  shut  off  and  the  mixture  is  admitted.  The  air 
supply  for  starting  is  kept  in  tanks  which  are  charged  to  a  pres- 
sure of  50  to  150  Ib.  by  a  small  compressor,  driven  either  from 
the  main  engine  shaft,  or  by  means  of  an  auxiliary  small  engine. 

In  starting  a  gas  engine  the  following  steps  should  be  taken, 
preferably  in  the  order  given: 


GAS  AND  OIL  ENGINES  117 

1.  The  fuel  supply  should  be  examined.     Cases  have  been 
known  in  which  an  operator  spent  considerable  time  hunting  for 
faults  in  the  ignition  system,  valve  setting,  etc.,  when  an  examina- 
tion of  the  gasoline  tank  would  have  revealed  the  fact  that  it  was 
empty. 

2.  The  ignition  system  should  be  tried  by  closing  the  switch 
disconnecting  the  end  of  one  of  the  wires  and  brushing  it  against 
the  binding  post  to  which  the  other  wire  is  attached.     A  good 
spark  should  have  a  blue-white  color.     If  the  spark  produced  is 
weak,  the  ignition  system  should  be  put  in  the  proper  condition. 

3.  The  lubricators  and  grease  cups  should  be  filled  and  ad- 
justed, so  that  the  proper  amount  of  oil  is  delivered  to  all  bear- 
ings and  moving  parts. 

4.  The  load  should  be  disconnected  from  the  engine  by  means 
of  a  friction  clutch  or  similar  device,  the  lubricators  turned  on, 
the  spark  retarded  to  the  starting  position,  and  the  starting  cam 
moved  into  place. 

5.  The  engine  is  now  ready  for  starting  by  either  of  the  methods 
previously  explained.     In  cranking,  always  pull  up  on  the  crank. 

6.  As  soon  as  the  engine  picks  up,  disengage  starting  cam,  turn 
on  cooling  water,  advance  spark  to  running  position  and  throw 
on  the  load  by  means  of  the  clutch. 

7.  Adjust  fuel  supply  so  that  the  engine  carries  its  load  with 
the  cleanest  possible  exhaust. 

To  stop  an  engine,  the  fuel  valve  is  closed,  the  ignition-system 
switch  is  opened,  the  lubricators  and  oil  cups  are  closed  and  the 
jacket  water  is  turned  off.  In  cold  weather  the  water  should  be 
drained  from  the  engine  jackets  to  prevent  freezing.  The  prac- 
tice of  draining  the  jackets  is  also  advisable  in  moderate  weather, 
as  this  tends  to  clean  the  jacket  from  the  deposit  of  sediment. 
Before  leaving  the  engine  it  should  be  cleaned,  all  parts  examined 
and  put  in  order  ready  for  starting  up. 

Causes  of  Gas  Engines  Failing  to  Start. — Failure  to  start  may  be 
due  to  one  or  more  of  the  following  causes : 

1.  Ignition  System  Out  of  Order. — This  may  be  caused  by  the 
switch  being  left  open,  by  a  loose  terminal,  by  a  disconnected 
wire,  by  a  broken  wire  the  insulation  being  intact,  by  the  ignition 
battery  being  weak  if  a  battery  is  used,  and  by  poor  timing  or 
wrong  connections  if  a  magneto  is  employed.  Other  causes  of 


118  FARM  MOTORS 

faulty  ignition  are  due  to  timer  slipping  on  the  shaft,  to  a  short- 
circuit  in  the  ignition  system,  to  carbonized  or  broken  spark 
points,  to  poor  timing  of  the  points  of  ignition.  In  the  case  of 
the  jump-spark  system,  ignition  will  also  be  prevented  if,  the 
points  on  the  spark  plug  are  too  far  apart,  the  spark  plug  is  dirty 
or  broken,  the  insulation  on  secondary  wires  is  poor,  induction  coil 
windings  are  broken  or  short  circuited,  vibrator  of  induction  coil 
is  not  properly  set. 

2.  An  engine  will  not  start  if  the  mixture  contains  too  much 
or  too  little  fuel. 

In  very  cold  weather  a  gasoline  engine  may  give  trouble  by  the 
fuel  not  vaporizing.  This  can  best  be  remedied  by  filling  the 
jackets  with  hot  water.  Do  not  bring  a  flame  near  the  carburetor 
or  gas  supply  pipe.  This  is  sometimes  recommended  for  start- 
ing in  cold  weather,  but  the  practice  is  a  dangerous  one. 

Improper  mixture  may  be  caused  by  slow  cranking,  in  which 
case  the  hand  placed  over  the  air  inlet  will  often  start  the  engine. 
Extra  priming  of  the  carburetor  may  also  aid  in  starting,  pro- 
vided care  is  taken  not  to  flood  the  engine  with  fuel. 

3.  Supply  pipes  clogged. 

4.  Dirt  or  water  in  the  fuel. 

5.  Pump  or  carburetor  out  of  order. 

6.  Water  in  carburetor. 

7.  Water  in  the  cylinder  due  to  leaky  jacket. 

8.  Inlet  valve  poorly  set  or  not  operating  due  to  broken  valve 
stem,  weak  or  broken  spring,  valve  sticking  or  broken. 

9.  Poor  compression  due  to  leaky  or  broken  piston  rings, 
improper  seating  of  valves,  or  to  other  leaks  from  the  cylinder 
to  the  outside. 

10.  If  the  exhaust  pipe  or  muffler  is  clogged,  the  engine  will 
fail  to  start. 

In  any  of  the  above  cases  the  remedies  are  self-evident. 

Causes  of  Motor  Failing  to  Run. — A  motor  will  sometimes  start, 
but  will  soon  afterward  slow  down  and  stop.  This  may  be  due 
to: 

1.  Fuel  tank  being  empty  or  fuel  pipe  becoming  clogged. 

2.  Poor  or  insufficient  lubrication,  which  may  cause  the  seizing 
of  the  piston  or  of  the  bearings. 

3.  Wire  being  jarred  loose  from  its  terminal,  timer  slipping  on 


GAS  AND  OIL  ENGINES  119 

shaft  or  to  some  other  fault  in  the  ignition  system,  such  as  weak 
cells,  or  vibrator  or  induction  coil  becoming  stuck. 

4.  Engine  carrying  too  great  a  load. 

Care  of  a  Gas  Engine. — It  is  best  to  keep  one  man  responsible 
for  the  care  of  an  engine  and  in  so  far  as  possible  confine  the 
operation  to  one  man.  The  engine  should  be  kept  clean  and 
all  the  parts  should  be  examined  frequently  to  see  that  everything 
is  in  the  best  working  order. 

If  an  engine  runs  well  at  no-load  but  will  not  carry  its  rated 
load,  this  may  be  due  to:  poor  compression,  poor  fuel,  defective 
ignition,  poor  timing  of  ignition,  incorrect  valve  setting,  incor- 
rect mixture,  leaky  inlet  or  exhaust  valves,  too  much  friction  at 
bearings,  or  to  engine  being  too  small  for  the  rated  load. 

The  operator  usually  can  tell  whether  the  correct  mixture 
is  being  admitted  into  the  cylinder  by  watching  the  exhaust. 
Black  smoke  issuing  from  the  exhaust  pipe  means  that  the  mix- 
ture is  too  rich  in  fuel.  This  should  be  remedied  by  decreasing 
the  amount  of  fuel  supplied  or  by  increasing  the  air  supply. 
Insufficient  fuel  in  the  mixture,  as  explained  in  the  section  on 
"Carburetors,"  will  cause  the  engine  to  miss  explosions  and  may 
even  cause  back-firing. 

Premature  ignition,  often  called  preignition,  is  due  to  the  de- 
position of  carbon  and  soot  on  the  walls  of  the  cylinder,  the  com- 
pression being  too  high  for  the  fuel  used;  by  overheating  of  the 
piston,  exhaust  valve,  or  of  some  poorly  jacketed  part. 

Deposition  of  carbon  on  the  cylinder  walls  is  usually  caused 
by  the  use  of  either  an  excessive  amount  or  a  poor  quality  of 
lubricating  oil.  This  will  not  only  cause  preignition,  but  may 
also  impair  the  action  of  the  valves,  igniter  and  piston  rings. 
Carbon  deposits  will  also  be  produced  if  the  mixture  is  too  rich. 

Insufficient  lubrication  may  result  in  abrading  surfaces  of 
piston  and  cylinder. 

It  is  well  not  to  economize  when  buying  gas-engine  cylinder 
oil.  Due  to  the  high  temperatures  developed  inside  the  engine 
cylinder  and  to  the  absence  of  moisture,  a  cylinder  oil  should  be 
selected  which  is  light  and  thin,  which  will  withstand  high  tem- 
peratures and  will  leave  no  carbon  deposits.  A  cylinder-lubricat- 
ing oil  well-suited  for  steam-engine  use  will  not  do  at  all  for  gas- 
engine  cylinder  lubrication. 


120  FARM  MOTORS 

For  the  bearings  and  other  wearing  parts  outside  the  cylinder, 
a  good  grade  of  machine  oil  will  be  found  satisfactory. 

A  blue  smoke  at  the  exhaust  indicates  that  too  much  cylinder 
oil  is  being  used. 

Pounding  in  gas  and  oil  engines  is  either  due  to  preignition,  the 
causes  of  which  were  outlined  above,  to  lost  motion  in  some 
bearing  of  the  engine,  or  to  the  engine  being  loose  on  its 
foundation. 

In  the  case  of  oil  engines  using  a  water  spray  with  the  fuel,  too 
little  water  will  result  in  preignition  and  consequent  pounding. 
This  should  be  remedied  by  supplying  more  water  with  the  fuel. 
Too  much  water  will  be  indicated  by  white  smoke  issuing  from 
the  exhaust  pipe. 

In  the  case  of  a  gasoline  engine,  white  smoke  at  the  end  of  the 
exhaust  pipe  usually  indicates  water  in  the  gasoline,  which  may 
be  due  to  a  leaky  jacket  or  to  some  other  cause. 

In  regard  to  the  temperatures  of  the  jacket  water,  this  depends 
on  the  compression  carried  and  on  the  size  of  the  engine.  With 
small  engines  of  the  hopper-cooled  type  the  jacket  temperature 
is  near  the  boiling-point  of  water.  Ordinarily  a  temperature  of 
about  150°F.  will  give  good  results.  It  is  advisable  to  use  cooling 
water  over  and  over  again,  since  after  several  circulations 
through  the  jackets,  the  impurities  contained  in  the  water  will 
have  been  precipitated. 

Problems:  Chapter  V 

• 

1.  What  is  an  internal-combustion  engine  and  how  does  this  form  of  motor 
differ  from  the  steam  engine? 
.  2.  Explain,  using  clear  sketches,  the  Otto  gas-engine  cycle. 

3.  Show  the  difference  in  construction  and  in  action  between  the  four- 
stroke   cycle  and  the  two-stroke  cycle  gas  engine.     Use  clear  sketches  to 
illustrate  the  important  working  parts. 

4.  What  is  gasoline  and  how  does  this  fuel  differ  from  kerosene? 

6.  What  is  denatured  alcohol?  How  do  the  calorific  values  of  alcohol  and 
of  gasoline  compare? 

6.  Discuss  the  use  of  alcohol  as  a  fuel  for  internal-combustion  engines. 

7.  Give  a  clear  sketch,  showing  the  important  parts  of  a  gasoline  engine. 
Name  all  parts. 

8.  Why  is  proper  carburetion  necessary  for  the  economical  and  reliable 
operation  of  a  gasoline  engine? 

9.  Sketch  and  describe  some  form  of  mixer  valve.     When  are  mixer  valves 
used?       • 


GAS  AND  OIL  ENGINES  121 

10.  Sketch   and   describe   a   concentric-type   float-feed    carburetor  and 
explain  in  detail  the  function  of  the  auxiliary  air  valve. 

11.  Describe  in  detail  carburetors  shown  in  Figs.  81  and  82. 

12.  Discuss  carbureting  kerosene  and  the  heavier  oils. 

13.  Sketch  and  explain  some  form  of  air-cooled  engine.     What  limits  the 
size  of  the  air-cooled  engine? 

14.  Give  directions  for  preparing  a  non-freezing  mixture  to  be  used  in  a 
water-jacketed  engine. 

16.  Explain  with  clear  sketches  the  make-and-break  system  of  ignition. 

16.  Explain,  using  sketches,  the  jump-spark  system  of  ignition. 

17.  What  is  the  difference  between  the  coils  used  in  the  make-and-break 
and  in  the  jump-spark  systems  of  ignition? 

18.  Give  wiring  diagrams  for  a  one-cylinder  make-and-break  ignition 
system,  operated  with  dry  cells  to  start  and  magneto  to  run  on. 

19.  Give  wiring  diagram  for  a  one-cylinder  jump-spark  ignition  system 
operated  with  a  dry  battery  to  start  and  a  magneto  to  run  on. 

20.  Explain  three  methods  for  lubricating  gas  engines. 
21o  Describe  two  systems  of  governing  gas  engines. 

22.  Describe  ten  uses  to  which  the  stationary  gasoline  engine  may  be  put 
by  a  farmer. 

23.  What  should  be  considered  when  selecting  a  gas  engine  for  farm  use? 

24.  Give  directions  for  installing  a  gasoline  engine. 

25.  Prepare  a  diagram  which  should  show  the  proper  crank  positions 
at  which  the  valves  should  open  and  close. 

26.  What  governs  the  point  of  ignition?     Give  approximate  rule  for 
setting  an  engine  operated  with  the  make-and-break  ignition  system  so  that 
the  spark  will  occur  at  the  proper  time. 

27.  Give  method  for  starting  by  hand,  easily,  a  gasoline  engine  of  10  hp. 
capacity. 

28.  Explain  causes  for  gas  engine  failing  to  start. 

29.  Explain  the  difference  between  preignition  and  back-firing. 

30.  Give  directions  for  operating  a  stationary  gas  or  oil  engine. 


CHAPTER  VI 
AUTOMOBILES 

Types  of  Automobiles. — An  automobile  can  be  propelled  by  a 
steam  engine,  by  an  internal-combustion  engine,  or  by  an  electric 
motor  with  current  secured  from  storage  batteries. 

The  majority  of  modern  automobiles  are  propelled  by  internal- 
combustion  engines  using  gasoline  as  fuel. 

Steam  and  electric  automobiles  operate  more  quietly,  are  more 
flexible,  and  can  be  more  easily  controlled  than  gasoline  auto- 
mobiles. Then,  the  electric  car  has  the  additional  advantage 
of  cleanliness  and  ease  of  starting,  while  the  steam  automobile 
has  a  greater  range  of  power  and  is  best-adapted  for  climbing 
hills. 

To  offset  the  above  advantages,  electric  cars  are  more  expensive 
to  operate,  and  can  be  run  only  for  short  distances  without  a  fresh 
charge  of  electricity.  They  are,  therefore,  used  mainly  in  cities 
and  in  other  places  where  facilities  are  available  for  the  charging 
of  storage  batteries. 

The  steam  automobile  requires  considerable  time  to  start  after 
a  long  stop,  as  steam  must  be  generated  in  the  automobile  boiler 
before  the  engine  will  start.  The  steam  automobile  must  also 
have  greater  skill  in  operating,  as  constant  attention  must  be 
given  to  the  fuel  and  the  water  supply. 

The  gasoline  automobiles  possess  the  advantage  that  they  are 
manufactured  in  many  different  types  and  designs,  and  can  be 
secured  at  a  great  variety  of  prices  from  several  hundred  up  to 
many  thousand  dollars  per  car.  Repair  parts  can  also  be  secured 
more  easily  for  gasoline  cars  than  for  any  other  type  of  auto- 
mobile. The  gasoline  automobile  is  more  economical  than  the 
steam  or  the  electric  car  and  is  usually  provided  with  a  fuel  supply 
of  sufficient  quantity  to  propel  the  car  several  hundred  miles. 

The  disadvantages  of  the  gasoline  automobile  are  that  it  is 
not  self-starting,  lacks  overload  capacity,  must  be  provided  with 
a  clutch,  as  a  gasoline  motor  will  not  start  under  load,  and  must 

122 


AUTOMOBILES  123 

be  built  with  a  complicated  system  of  gears  for  changing  speed 
and  for  reversing. 

This  chapter  will  be  devoted  mainly  to  the  consideration  of  the 
gasoline  automobile,  as  steam  and  electric  automobiles  are  seldom 
used  in  rural  communities. 

Essential  Parts  of  a  Gasoline  Automobile. — The  essential 
parts  of  an  automobile  are : 

1.  Power   plant,    which   consists   of   an  internal-combustion 
engine  and  its  auxiliaries,  such  as  the  fuel  system,  carburetor, 
ignition  system,  cooling  and  lubricating  systems,  and  starting 
systems. 

2.  Friction  clutch,  for  disengaging  the  engine  from  the  propel- 
ling gear. 

3.  Transmission    mechanism,    for    speed-changing    and    for 
reversing. 

4.  Differential  or  compensating  gear,  the  purpose  of  which  is 
to  allow  one  drive  wheel  to  revolve  independently  of  the  other, 
this  being  necessary  when  turning  corners. 

5.  Front  and  rear  axles. 

6.  The  frame  which  supports  the  power  plant,  transmission 
system,  and  body  of  the  car.     The  frame  is  attached  to  springs 
which  in  turn  are  attached  to  the  axles.     The  springs  are  built 
jip  from  a  number  of  broad  and  thin  leaves. 

7.  Control  system,  which  is  made  up  of  the  steering  mechanism 
as  well  as  of  the  hand  levers  and  foot  pedals  for  controlling  the 
spark   position,    carburetor   throttle,    clutch   and   transmission 
gearing. 

8.  Body,  top,  fenders,  hood,  dash,  running  board,  front  and 
rear  wheels,  tires,  lighting  system,  tool  chest,  tools,  wind  shield, 
speedometer  and  odometer  for  showing  speed  per  hour  and  total 
distances,  alarm  and  similar  equipment  and  accessories,  which 
are  found  on  the  majority  of  automobiles. 

Automobiles  are  required  by  law  to  carry  two  lights  in  front 
and  one  rear,  or  tail  light.  The  tail  light  is  for  the  purpose  of 
preventing  rear-end  collisions. 

The  term  chassis  is  applied  to  the  car  with  the  body  and  ac- 
cessories removed  (Figs.  118  and  119).  The  chassis  shown  in 
Fig.  118  is  an  automobile  chassis  and  the  power  is  transmitted 
from  the  motor  to  the  rear  axle  by  means  of  a  shaft  drive.  In  the 


124 


FARM  MOTORS 


case  of  auto  trucks  the  power  from  the  motor  to  the  axle  is  trans- 
mitted by  worm  or  chain  drive  (Fig.  119). 


Automobile  Motors. — Automobile  motors  are  usually  of  the 
multiple-cylinder  vertical  types  of  internal-combustion  engines 


AUTOMOBILES 


125 


which  operate  on  the  Otto  four-stroke  cycle.  The  motor  is 
located  in  the  front  of  the  automobile  frame,  for  accessibility  and 
for  the  purpose  of  balancing  the  weight  in  the  rear  part  of  the 


car. 


The  earlier  automobiles  employed  one-cylinder  engines,  but 
the  modern  automobile  motor  consists  of  four,  six,  eight,  or 


twelve  vertical  cylinders,  as  multi-cylinder  machines  start  easier, 
operate  more  smoothly,  run  with  less  vibration,  and  have  a 
wider  range  of  power  and  speed. 
In  the  case  of  four-  and  six-cylinder  motors,  all  the  cylinders 


126 


FARM  MOTORS 


FIG.  120. — Four  cylinder  automobile  motor. 


FIG.  121. — Cylinders  at  an  angle  of  90°. 


A  UTOMOBILES 


127 


are  usually  located  on  one  side  of  the  crankshaft  (Fig.  120). 
Eight-  and  twelve-cylinder  motors  are  arranged  with  the  cylinders 
in  two  rows.  Eight-cylinder  machines  are  usually  set  as  shown 


FIG.  122. — Automobile  motor,  cylinders  cast  singly. 


FIG.  123. — Motor  with  cylinder  en-bloc. 

in  Fig.  121  with  the  -cylinders  at  an  angle  of  90°.     The  twelve- 
cylinder  motors  are  usually  set  with  the  cylinders  at  an  angle  of  60°. 
Automobile  motor  cylinders  are  cast  singly   (Fig.   122),  or 
en-bloc,  which  means  that  several  cylinders  are  cast  in  one  piece 


128 


FARM  MOTORS 


(Fig.  123).     The  simple  cylinder  casting  is  light  in  weight,  can  be 
easily  repaired,  and  is  better  adapted  for  the  thermo-syphon 

system  of  cooling.  The  en-bloc 
motor  is  more  rigid,  occupies  less 
space,  and  is  more  commonly  used 
on  modern  automobiles. 

Automobile  motors  are  most 
commonly  water-cooled  and  are 
provided  with  radiators  (Fig.  124) 
for  the  purpose  of  cooling  the 
water  after  it  has  absorbed  heat 
from  the  cylinder  walls.  There 
are  two  systems  of  cooling  auto- 
mobile motors: 


FIG.  124. — Automobile  radiator. 


1.  The  thermo-syphon  water-circulation  system   (Fig.    125) 
depends  upon  the  fact  that   water  rises   when   heated.     The 


FIG.  125. — Thermo-syphon  water-circulationjsystem. 

system  does  not  require  a  force  pump  to  circulate  the  water.  The 
water  enters  the  cylinder  jackets  at  A.  Upon  becoming  heated 
by  the  explosions  going  on  within  the  cylinder  of  the  engine,  the 
water  rises  to  the  top,  entering  the  pipe  B  and  passing  into  the 


AUTOMOBILES 


129 


radiator  at  C,  where  it  is  brought  into  contact  with  the  larger 
cooling  surface  D.     On  being  cooled,  the  water  becomes  heavier 


FIG.  126.— Air-cooled  automobile  motor. 

and  sinks  to  the  bottom  of  the  cooling  system,  to  enter  the  cylin- 
der once  more  and  to  repeat  its  circulation.  The  cooling  action 
is  further  increased  by  a  belt-driven 
fan  (F)  which  draws  air  through  the 
radiator  spaces. 

2.  The  forced  circulation  system 
depends  upon  a  pump,  driven  by  the 
engine,  to  keep  the  water  in  constant 
circulation  through  the  engine  jacket 
and  radiator.  This  system  is  more 
positive  in  its  action  and  is  not  in- 
fluenced by  obstructions  as  is  the 
thermo-syphon  system. 

In  one   successful  type  of  auto-  Fra-  127-~™°j?*swiih  P°PPe' 
mobile,  the  cylinders  are  cast  simply 

with  ribs  and  are  air-cooled.     The  circulation  of  the  air  is  pro- 
duced by  means  of  a  fan  in  the  motor  flywheel  (Fig.  126). 

Three  types  of  valves  -are  used  on  automobile  motors.     These 
are  the  poppet,  the  sleeve  and  the  rotary. 


130 


FARM  MOTORS 


The  poppet  valve  (Fig.  127)  is  most  commonly  used  and  is 
similar  to  the  valves  used  on  stationary  gasoline  engines. 

Fig.  128  illustrates  the  fundamental  parts  of  the  sleeve-valve 
type  of  motor.  The  sleeves  slide  up  and  down  between  the  main 


8     9 


29 


!  0 


15 


18 


1.  Cylinder. 

2.  Water- jacketed    cylinder 

head. 

3.  Spark  plug. 

4.  Inner  sleeve. 

5.  Outer  sleeve. 

6-7.  Port  openings  in  sleeves. 

8.  Priming  cup. 

9.  Oiling  grooves  in  sleeves. 

10.  Port  opening  in  cylinder. 

11.  Connecting-rod  operating 

outer  sleeve. 

12.  Connecting-rod  operating 

inner  sleeve. 


13.  Fly  wheel. 

14.  Oil  trough  adjusting  lever 

connected  to  throttle. 

15.  Lower  part  of  crank  case, 

containing      oil      pump, 
strainer  and  piping. 

16.  Oil  scoop. 

17.  Adjustable  oil  troughs. 

18.  Crank  shaft. 

19.  Crank-shaft  bearing. 

20.  Starting  clutch. 

21.  Silent     chain     drive     for 
magneto  shaft. 


22.  Silent  chain  driving  sprock- 

et for  electric  generator 
(on  4-cylinder  models). 

23.  Silent     chain      drive     for 

eccentric  shaft. 

24.  Eccentric  shaft. 

25.  Connecting  rod. 

26.  Bearing  for  eccentric  shaft. 

27.  Piston. 

28.  Piston  rings. 

29.  Cylinder-head  ring    (junk 

ring). 


FIG.  128. — Sectional  view  of  Stearns-Knight  four-cylinder  motor. 

engine  piston  and  the  cylinder  walls.     The  various  parts  are 
named  in  Fig.  128. 

The  rotary  form  of  valve  (Fig.  129)  is  little  used.  This  type  of 
valve  consists  of  a  slotted  cylinder  which,  when  rotating,  opens  a 
passage  for  the  gases. 


AUTOMOBILES 


131 


FIG.  129. — Motor  with  rotary 
valves. 


FIG.  130.— Tee-head  cylinder. 


FIG.  131.— Ell-head  cylinder.  FIG.  132.— Valves-in-the-head 

cylinder. 


132 


FARM  MOTORS 


Automobile  motors  with  poppet  valves  are  built  in  three  forms: 

1.  The  tee-head  form  (Fig.  130)  with  valves  on  opposite  sides. 
This  type  of  motor  usually  has  two  camshafts  for  operating 
the  valves,  but  allows   the  use  of  larger   valves.     The   com- 
pressing chamber  is  irregularly  shaped  in  this  type  of  motor. 

2.  The  ell-head  motor  (Fig.  131).     This  form  of  motor  has 


both  valves  on  the  same  side  of  the  cylinder  and  these  valves  are 
operated  by  a  single  camshaft. 

3.  The  valve-in-the-head  type  of  motor  (Fig.  132).  This  type 
of  motor  has  a  very  compact  compression  chamber,  but  is  more 
noisy  than  the  other  types  on  account  of  the  rocker  arms  and 
push  rods. 

Clutches. — The  clutch  is  a  device  used  for  connecting  the 
engine  shaft  to,  and  disconnecting  it  from,  the  propelling  gear  of 


AUTOMOBILES 


the  car.     Clutches  depend  upon  the  frictional  adhesion  between 
surfaces  and  are  of  the  following  types: 

1.  The  cone  clutch  (Fig.  133)  consists  of  a  leather-faced  cone  C 
which  is  pressed  by  the  spring  S  against  the  inside  of  a  tapered 
rim  of  a  flywheel  (Tf). 

2.  The  multiple-disk  clutch  (Fig.  134)  depends  on  its  action 
upon  the  friction  between  disks.     Alternate  disks  are  fastened  to 
the  driving  and  driven  parts.     The  disks  marked  A  are  fastened 


FIG.  134.— Multiple-disk  clutch. 

to  the  engine  shaft  and  those  marked  B  connect  with  the  mechan- 
ism to  be  driven.  If  the  clutch  runs  in  a  bath  of  oil,  it  is  called  a 
wet-disk  clutch.  A  spring  is  employed  to  hold  the  disks  in  con- 
tact when  the  clutch  is  in  action. 

3.  The  expanding  clutch  has  an  annular  ring  which,  by  expand- 
ing, connects  the  driving  and  driven  shafts.  This  type  of  clutch  is 
seldom  used. 

Clutches  are  not  necessary  on  automobiles  which  are  propelled 
by  steam  engines  or  by  electric  motors,  as  the  supply  of  steam  01 


134 


FARM  MOTORS 


of  electricity  is  generated  outside  the  motors  proper  and  can  be 
varied  to  suit  the  requirements  of  speed  and  load. 

Transmission  Gears. — The  speed  of  an  internal-combustion 
engine  and  its  direction  of  rotation  cannot  be  varied  to  meet  the 
requirements  of  a  self-propelled  vehicle.  This  necessitates  the 
introduction  of  a  speed-changing  and  reversing-gear  mechanism, 
so  that  different  speed  ratios  can  be  secured  between  the  engine 
and  the  drive  axle. 

From  the  definition  of  power  (Chapter  II),  it  is  evident  that  a 
motor  of  a  given  power,  in  order  to  overcome  increasing  resist- 
ance, must  propel  the  car  at  a  less  speed.  This  means  that  the 
speed  of  the  car  must  be  reduced,  by  shifting  the  speed-changing 
gears,  when  the  automobile  must  climb  hills  or  overcome  other 
obstructions  incidental  to  the  road  conditions  over  which  the  car 


FIG.  135. — The  progressive  sliding-gear  transmission  system. 

is  operated.  Before  shifting  the  gears  of  the  transmission  system, 
the  friction  clutch  should  be  thrown  out. 

Transmission  gears  are  of  four  types:  namely,  the  progressive 
sliding  gear,  the  selective  sliding  gear,  the  planetary  gear,  and 
the  friction  drive. 

The  Progressive  Sliding-gear  Transmission  System. — The 
change  of  gears  is  carried  on  in  progressive  steps.  Fig.  135 
illustrates  a  progressive  transmission  system.  A  is  the  driving 
•shaft,  which  derives  its  power  from  the  motor  and  through  the 
friction  clutch.  B  is  the  driver  or  propeller  shaft  which  trans- 
mits the  power  to  the  rear  axle.  The  gears  C  and  D  are  fastened 


AUTOMOBILES 


135 


together  and  can  be  slid  by  means  of  a  lever  L  along  the  main 
shaft,  which  is  square.  If  D  on  the  main  shaft  is  shifted  so 
that  it  is  in  mesh  with  E  on  the  countershaft  and  the  shaft  A 
is  rotated,  the  shaft  B  will  rotate  in  the  same  direction  but 
more  slowly.  If  the  gears  C  and  D  are  shifted  so  that  C  will 
engage  K,  the  countershaft  F  will  turn  the  shaft  B4.  at  a  slower 
speed  than  when  D  and  E  were  in  mesh.  If  the  gears  C  and  D  are 
shifted  so  that  C  meshes  with  R,  A  and  B  will  revolve  in  the  oppo- 
site directions,  thus  propelling  the  car  backward.  If  the  gears  C 
and  D  are  moved  to  the  left  until  the  lugs  on  D  and  on  H  engage, 
shafts  A  and  B  will  turn  as  one  shaft  and  the  car  will  be  propelled 
at  the  high  speed  forward. 


FIG.  136. — The  selective  sliding-gear  transmission  system. 

The  Selective  Sliding-gear  Transmission  System. — The  de- 
sired speed  can  be  secured  without  shifting  through  other  gear 
positions  as  in  the  progressive  system.  This  system  is  used  on  the 
largest  number  of  automobiles. 

In  Fig.  136,  A  is  the  driving  shaft,  B  the  driven  shaft.  S  and 
L  are  slides  carrying  yokes  that  move  the  wheels  D  and  K.  All 
the  wheels  on  the  countershaft  are  fast  to  the  shaft.  A  lever  is 
arranged  for  shifting  either  S  or  L  and  for  allowing  the  various 
gears  on  the  shaft  B  to  mesh  with  those  on  the  countershaft. 
This  system  is  commonly  arranged  for  three  speeds  forward  and 
one  speed  reverse,  but  can  be  modified  to  give  any  number  of 


136 


FARM  MOTORS 


speeds  for  forward  and  for  reversing.     Fig.   137  illustrates  a 
selective  transmission  system  and  multiple-disk  type  clutch. 


FIG.  137.— Transmission  system  and  clutch. 


FIG.  138. — Planetary  transmission  system. 

The  Planetary  Transmission  System. — In  the  planetary  system 
of  transmission  the  speed  changes  do  not  depend  upon  the 


AUTOMOBILES  137 

shifting  of  gears,  but  clutches  or  brakes  are  employed  for  holding 
certain  wheels  in  position.  The  drive  is  positive,  and  the  gears 
are  always  in  mesh. 

The  planetary  system  is  particularly  well- adapted  for  high 
speeds,  as  the  entire  system  is  clamped  solidly  and  revolves  with 
the  motor  crankshaft  as  a  single  mass,  when  the  car  is  propelled 
at  high  gear;  no  gears  are  turning  idly,  and  the  transmission 
system,  by  its  weight,  serves  to  steady  the  rotation  of  the  motor. 

The  objections  to  the  planetary  system  are  that  it  provides 
only  two  forward  speeds  and  one  reverse  speed,  and  is  not  efficient 
on  low  and  reverse  speeds,  on  account  of  the  power  absorbed  by 
the  friction  between  the  clutches  and  the  gears.  This  system  is 
used  mainly  on  small  automobiles. 

A  planetary  transmission  system,  which  is  used  in  a  Ford 
automobile,  is  illustrated  in  Fig.  138.  Brakes  applied  by  means 
of  foot  pedals  are  used  for  holding  certain  of  the  gears  stationary 
for  low  speed  and  for  reverse.  For  high  speed  forward,  the 
friction  clutch,  which  is  of  the  multiple-disk  type  and  is  part  of 
the  planetary  system,  connects  directly  the  driving  and  driven 
shaft. 

The  Friction  Drive. — The  friction-drive  form  of  transmission  is 
illustrated  in  Figs.  139  and  140  and  depends  upon  the  friction 
between  rolling  surfaces. 

A  flat-faced  disk  A  is  carried  on  an  extension  of  the  engine 
shaft.  The  other  part  of  the  transmission  consists  of  a  fiber-faced 
friction  wheel  B  which  can  be  slid  along  the  shaft  S  and  brought 
into  frictional  engagement  with  the  disk  A.  The  power  is  trans- 
mitted from  the  shaft  S  to  the  driving  wheels  by  a  chain  (C)  and 
sprocket  wheel,  or  by  bevel  gears  and  a  propeller  shaft.  As  the 
wheel  B  is  moved,  by  the  aid  of  the  lever  L,  nearer  the  center  of  the 
disk  A,  the  shaft  S  rotates  more  slowly;  shifting  the  wheel  B 
nearer  to  the  outer  edge  of  the  disk  A,  Sis  rotated  faster.  Sliding 
B  to  the  right  of  the  center  of  A  reverses  the  direction  of  rota- 
tion of  the  shaft. 

The  chassis  of  an  automobile  with  friction  drive  is  illustrated 
in  Fig.  140. 

The  friction  drive  is  the  simplest  of  all  forms  of  transmission, 
is  inexpensive,  is  more  silent  and  permits  the  propulsion  of  the 
car,  at  an  unlimited  number  of  speeds  in  either  direction.  The 


138 


FARM  MOTORS 


FIG.  139. — Friction  drive. 


FIG.  140. — Chassis  of  automobile  with  friction  drive. 


AUTOMOBILES 


139 


disadvantages  of  this  system  are  that  the  drive  is  not  absolutely 
positive,  that  there  is  a  loss  of  power  due  to  slipping,  that  fric- 
tional  surfaces  wear  rapidly,  and  that  the  system  cannot  be  prop- 
erly enclosed.     The  friction  drive  is  used  mainly  on  light  cars. 
Differentials  for  Automobiles. — When  an  automobile  turns  a 


,c  Z"   fi 

5 

FIG.  141. — Bevel-gear  differential. 


corner,  the  drive  wheel  on  the  outside  of  the  curve  must  turn 
faster  than  that  on  the  inside.  If  the  two  drive  wheels,  which  are 
the  rear  wheels,  were  rigidly  connected,  one  would  have  to  skid 
or  slip  when  turning  a  corner  or  when  going  over  an  obstruction; 
this  would  throw  a  great  strain  on  the  front  axles  and  wheels  with 


140 


FARM  MOTORS 


consequent  wear  on  the  tires.  The  differential,  sometimes  called 
a  compensating  or  equalizing  gear,  allows  one  drive  wheel  to 
move  ahead  of  the  other  when  turning  a  corner  or  when  over- 
coming resistances  due  to  the  unevenness  of  the  road,  while  at 
the  same  time  both  wheels  are  driven  from  the  engine. 


FIG.  142. — Spur-gear  differential. 

There  are  two  types  of  automobile  differentials,  the  bevel- 
gear  type  and  the  spur-gear  type. 

The  bevel-gear  type  of  differential  (Fig.  141)  is  most  commonly 
used.  The  rear  axle  S  is  divided  into  two  halves.  Each  half  of 
the  rear  axle  carries  a  drive  wheel  at  its  outer  end  and  a  bevel 


AUTOMOBILES  141 

gear  (C  or  D)  at  its  inner  end.  The  two  bevel  gears  C  and  D 
are  connected  by  three  or  four  differential  or  compensating 
pinions  (B,  B,  B)  which  are  placed  at  equal  distances  apart 
around  the  circle.  These  bevel  pinions  (B}  B,  B)  are  capable  of 
rotating  loosely  on  radial  studs  which  are  fastened  at  their  outer 
ends  to  the  casing  or  housing  0.  Gear  A  is  made  to  turn  loosely 
upon  the  hubs  of  bevel  gears  C  and  D  but  is  made  fast  to  the 
casing  or  housing  0  by  means  of  bolts.  The  power  from  the 
engine  is  transmitted  to  the  housing  0  through  the  bevel  gear  P 
which  meshes  with  gear  A.  The  housing  transmits  this  power 
through  the  small  bevel  pinions  (B,  B,  B)  to  the  bevel  gears  C 
and  Dj  which  are  connected  to  the  rear  wheels  or  drive  wheels. 

On  a  level  road  with  both  drive  wheels  rotating  .at  the  same 
speed,  the  housing  0  with  the  gears  and  pinions  will  revolve  as 
one  mass  and  the  small  pinions,  marked  B}  will  remain  stationary. 
In  turning  a  corner,  in  meeting  an  obstruction,  or  in  case  one  of 
the  wheels  slips,  if  the  drive  wheel  attached  to  the  bevel  gear  C 
must  turn  slower  than  that  attached  to  gear  D,  the  differential 
pinions  (B,  Bt  B)  will  revolve  on  their  axes.  The  bevel  pinions 
(B,  Bj  B)  act  as  balance  levers,  similar  to  the  doubletrees  or 
eveners  on  a  team  of  horses,  dividing  the  torque  between  the  two 
bevel  gears  (C,  D)  and  allowing  the  two  drive  wheels  to  run  at 
different  speeds. 

The  spur-gear  type  of  differential,  now  seldom  used,  is  shown 
in  Fig.  142.  The  power  from  the  engine  is  transmitted  to  the 
housing  0  through  the  bevel  gear  P,  which  meshes  with  the  gear 
A.  The  housing  transmits  this  power  through  the  small  spur 
pinions  (B,  B,  B)  to  the  spur  gears  C  and  D,  which  are  connected 
with  the  drive  wheels.  The  action  of  this  differential  is  similar 
to  the  bevel-gear  differential  of  Fig.  141. 

The  relative  positions  of  the  transmission,  the  differential, 
and  the  driving  wheels  are  illustrated  in  Fig.  143. 

Universal  Joint. — Since  the  engine  and  the  gearing  are  mounted 
on  the  frame  of  the  automobile,  while  the  driving  wheels  are 
connected  to  the  frame  by  springs,  automobiles  with  shaft  drive 
must  be  provided  with  some  flexible  joint.  The  universal  joint 
(Fig.  143),  which  consists  of  forked  arms  at  the  ends  of  shafts, 
and  at  right  angles  to  each  other,  permits  the  lower  end  of  the 
propeller  shaft  to  move  independently  of  the  motion  of  the  rear  axle. 


142 


FARM  MOTORS 


"Propeller  shaft"   (Fig.  143)  is  the  term  applied  to  the  shaft 
which  connects  the  transmission  with  the  differential. 


Front  and  Rear  Axles. — The  front  axles  are  of  a  construction 
which  permits  the  wheels  to  pivot  near  the  hub.  With  this 
construction  there  is  not  the  tendency  for  the  wheel  to  swing 


AUTOMOBILES 


143 


around  when  striking  an  obstruction  in  the  road.  The  steering 
knuckles  are  a  part  of  the  front  axle,  on  which  the  front  wheels 
revolve.  Steering  arms  are  inserted  in  the  knuckles  and  con- 
nect together  with  an  adjustable  tie-rod  so  that  both  knuckles 
turn  simultaneously.  A  third  arm  attached  to  the  left-hand 
knuckle  connects  the  steering  gear  by  means  of  the  steering 
connecting  rod.  In  Fig.  144  the  various  parts  of  the  front 
axles  are  illustrated.  Some  front  axles  are  constructed  of  heavy 
steel  tubes,  with  dropped  forged  axle  ends.  The  majority  of 
automobiles  are  constructed  with  front  axles  which  are  drop- 
forged  I-beam  sections  (Fig.  144). 


FIG.  144. — Details  of  front  axle. 

The  rear  axle  of  the  automobile  carries  the  differential  and  the 
two  rear  wheels.  In  one  type  of  rear  axle,  called  the  semi- 
floating  type,  the  axles  carry  the  entire  load.  In  the  full-float- 
ing axle  the  weight  of  the  car  is  carried  by  a  housing  through 
which  the  axle  passes.  In  the  full-floating  axle  the  shaft  may 
be  removed  without  disturbing  the  wheel  or  the  differential. 

Steering  and  Control  Systems. — Automobiles  are  steered  by 
means  of  a  hand  wheel  which  is  located  on  the  top  of  the  steering 
column.  The  steering  gear  operates  on  the  front  axle,  through 
the  steering  connecting  rod,  and  turns  the  knuckles  and  front 
wheels.  The  steering  column  (Fig.  145)  usually  contains  several 
concentric  tubes  with  connections  to  the  alarm,  the  throttle 
control,  the  spark  control,  and  the  steering  mechanism  which 
reduces  the  motion  of  the  steering  wheel. 


144 


FARM  MOTORS 


Sector 


•Spark  fever 

/     Throttle,  fever 

}*•          //' 


FIG.  145. — Steering  gear. 


AUTOMOBILES 


145 


The  worm-and-nut  form  of  steering  gear  (Fig.  145)  consists 
of  a  double-threaded  worm  attached  to  the  hand  wheel  and  two 
half  nuts,  one  of  which  has  a  right-handed  thread  and  the  other 
a  left-handed  thread.  If  the  steering  wheel  is  turned,  one  of  the 
half  nuts  moves  up  and  the  other  down,  thus  turning  the  steering 
yoke  and  moving  the  pitman  arm  back  and  forth.  The  motion 
of  the  pitman  arm  is  transmitted  to  the  steering  knuckles  and 
front  wheels..  _^ 

Another  form  of  steering  gear  consists  of  a  worm-and-worm 
gear  (Fig.  146).  The  worm-gear  shaft  carries  the  pitman  arm, 


For  grease 


FIG.  146. — Worm-and-worm-gear  steering  mechanism. 

which  transmits  the  motion  of  the  steering  wheel  to  the  steering 
knuckles  and  to  the  front  wheels. 

The  spark  and  the  carburetor  throttle-control  levers  are  Usually 
located  on  top  of  the  steering  wheel  (Fig.  145),  but,  in  some  few 
makes  of  cars,  under  the  wheel  on  the  steering  post.  The  speed 
of  the  automobile  motor  is  controlled  by  the  throttle  and  spark 
levers. 

The  largest  number  of  cars  are  provided  with  two  methods  of 
throttle  control,  the  hand  throttle-control  lever  on  the  steering 
wheel  and  a  foot  control  of  the  throttle,  commonly  called  the 
10 


146 


FARM  MOTORS 


accelerator.  The  foot  throttle-control  lever  is  usually  employed 
when  shifting  the  transmission  gears,  as  one  hand  is  required  to 
operate  the  gear-shifting  lever  while  the  other  is  engaged  in  steer- 
ing the  car.  The  accelerator  is  also  used  when  running  an 
automobile  through  crowded  streets.  The  hand  throttle  lever 
and  the  accelerator  are  interconnected,  so  that  the  accelerator 
will  move  up  or  down  if  the  hand  throttle  lever  is  shifted. 
The  control  system  (Fig.  147)  includes  a  pedal  for  operating 


Gear  shifting  lever 


Emergency  brake  lever  J 

Muffler  cut  outl 


Brake  pedal 
»  Clutch  pedal 
Accelerator 


FIG.  147. — Automobile  control  system. 

the  friction  clutch,  one  for  operating  the  service  brake,  a  lever 
for  operating  the  emergency  brake,  and  a  lever  for  operating  the 
speed-changing  and  reversing  gears  of  the  transmission. 

The  Ford  automobile  is  controlled  by  three  foot  pedals  and 
by  one  hand  lever.  The  pedals  operate  the  clutch,  the  reverse, 
and  the  service  brake.  The  hand  lever  operates  the  clutch  and 
the  emergency  brake. 

Brakes. — Automobile  tires  being  made  of  rubber,  the  brakes 
are  not  applied  to  the  wheel  tires  but  to  metal  drums  which  are 
usually  fastened  to  the  rear  wheels.  Two  brakes  are  employed. 
One  brake,  called  the  service  or  running  brake,  is  operated 
by  means  of  a  foot  pedal.  The  other  brake,  called  the  emergency 
brake,  is  operated  by  a  hand  lever  and  is  intended  for  use  only  in 


AUTOMOBILES 


147 


case  the  service  brake  fails  or  in  case  a  very  strong  braking 
action  is  required.  Automobiles,  with  the  planetary  system  of 
transmission  (Fig.  138),  have  the  service-brake  drum  near  the 
transmission  mechanism. 

The  braking  effect  can  be  produced  by  expanding  the  brake 
band  or  shoe  within  the  brake  drum  or  by  contracting  the  brake 
shoe  around  the  outside  of  the  drum. 

The  brake  bands  are  usually  covered  on  the  rubbing  side  with 
an  asbestos  preparation,  which  can  be  replaced  when  worn  out. 


S0M& BRtKF... 
ADJUSTING  NUT 


BRAKEBAND        • 
•S£RVIC£  BMfffLJMMf 


FIG.  148. — Section  of  brake. 

The  brakes  in  Fig.  148  consist  of  an  external  service  brake 
and  an  internal  emergency  brake. 

Wheels  and  Tires. — Automobile  wheels  are  made  of  wood  or  of 
metal.  The  wooden  wheels  are  considered  more  flexible,  but  the 
metal  wheels  are  lighter. 

Tires  made  of  rubber  are  used  to  take  up  the  road  vibrations 
before  they  reach  the  car  proper. 

The  double  pneumatic  rubber  tire  is  used  on  gasoline  automo- 
biles, while  the  solid  rubber  tire  is  employed  to  a  limited  extent 
on  trucks  and  on  electric  automobiles.  The  double  automobile 
pneumatic  tire  consists  of  an  inner  rubber  tube  with  a  check  valve 
to  hold  the  air  and  an  outer  casing  which  protects  the  inner 
tube  from  wear.  The  outer  casing  is  built  up  of  strong  canvas 
fabric  covered  with  a  tougher  and  denser  rubber  than  the  inner 
tube. 

Single-tube  pneumatic  tires,  similar  to  bicycle  tires,  have  been 
used  to  some  extent  on  automobiles.  Double  tires  are  preferable 
on  account  of  the  security  of  their  attachment  to  the  wheel  rim. 


148  FARM  MOTORS 

In  bicycles  the  single  tire  is  practical  as  the  danger  of  the  tires 
rolling  off  the  rim  is  averted  by  the  inclination  taken  by  the 
entire  wheel  when  turning  corners. 

The  tread  of  automobile  wheels  is  usually  56  in.,  measured 
from  wheel  center  to  wheel  center  when  the  tires  touch  the 
ground. 

Carburetors  and  Gasoline  Feed  Systems. — Automobile  car- 
buretors are  of  the  float-feed  type  and  are  usually  of  the 
forms  described  in  Chapter  V  and  illustrated  in  Figs.  78  to  81. 
Multiple-nozzle^  carburetors  are  adapted  for  high-powered 
automobiles. 

The  carburetor  throttle,  as  previously  explained,  can  be  con- 
trolled by  the  accelerator  as  well  as  by  the  hand  throttle  lever 
on  the  steering  post.  With  the  pressure  removed  from  the 
accelerator,  the  carburetor  throttle  will  close  to  the  position  set 
by  a  hand  throttle  lever. 

To  meet  the  requirements  of  the  lower  grades  of  gasoline, 
automobile  carburetors  are  often  jacketed  and  the  air  supply  is 
preheated  by  the  exhaust  gases. 

The  concentric  types  of  float-feed  carburetor  (Figs.  78,  80  and 
81)  are  much  used,  as  the  fuel  level  in  the  float  chamber  is  not 
affected  by  the  inclination  of  the  car.  A  carburetor  should  be  of 
the  proper  size  for  the  automobile  motor.  If  the  carburetor  is 
too  large,  the  fuel  economy  and  the  engine  capacity  will  be  re- 
duced, as  the  air  velocity  through  the  mixing  chamber  would 
be  too  low  to  produce  the  proper  mixture  of  air  and  fuel.  A  car- 
buretor too  small  for  the  engine  it  is  to  serve  will  chill  on  account 
of  insufficient  heat  supplied  by  the  entering  air  and  this  will 
also  result  in  poor  fuel  economy  and  loss  of  power. 

The  following  systems  are  used  for  feeding  fuel  from  the  gaso- 
line tank  to  the  carburetor : 

1.  The  Gravity-feed  System. — The  gasoline  tank  is  placed  above 
the  level  of  the  carburetor  and  the  fuel  flows  by  gravity.     This 
system  is  simple,  but  when  the-  fuel  tank  is  placed  under  the 
seat,  the  pressure  on  the  carburetor  float  valve  is  not  constant, 
and,  in  ascending  hills,  the  gasoline  supply  may  become  inter- 
rupted.    Sometimes  this  difficulty  is  overcome  by  placing  the 
fuel  tank  in  the  cowl,  the  space  back  of  and  above  the  engine. 

2.  Pressure-feed  -System. — The  fuel  tank  is  placed  at  the  rear 


AUTOMOBILES  149 

of  the  car  and  the  gasoline  is  forced  to  the  carburetor  by  pressure. 
The  initial  pressure  is  secured  by  an  air  pump,  and  after  the 
engine  is  in  operation  the  exhaust  gases  create  the  necessary 
pressure.  A  safety  valve  keeps  the  pressure  within  the  required 
intensity.  This  system  is  positive  and  the  fuel  is  supplied  to  the 
carburetor  regardless  of  the  position  of  the  car,  but  the  pressure 
interferes  with  the  proper  operation  of  the  float. 

3.  Vacuum-feed  System. — The  suction  stroke  of  the  engine  is 
utilized  to  lift  gasoline  from  the  fuel  tank  to  the  auxiliary  tank 
near  the  engine,  from  which  the  fuel  flows  to  the  carburetor  by 
gravity.  This  system  has  all  the  advantages  of  the  pressure- 
feed  system  and  is  more  reliable.  It  is  also  superior  to  the 
gravity  system  in  that  the  gasoline  supply  is  independent  of  the 
position  or  location  of  the  fuel  tank. 

Ignition. — The  jump-spark  electric  system  of  ignition  (Chapter 
V)  is  employed.  In  some  makes  of  automobiles,  batteries  are 
used  for  furnishing  "current  in  starting  and  magnetos  supply 
electricity  for  ignition,  after  the  motor  has  attained  normal 
speed.  This  is  called  the  dual  system. 

The  voltage  of  a  magneto  increases  with  its  speed,  and  this 
makes  it  desirable  to  employ  a  battery  for  starting. 

The  advantages  of  magneto  ignition  are  positive  action,  low 
upkeep,  and  simplicity.  Magnetos  can  be  constructed  so  as  not 
to  require  hand  advance  of  the  spark.  Various  types  of  low- 
tension  and  high-tension  magnetos  (Chapter  V)  are  used  for 
igniting  the  mixture  in  an  automobile  engine. 

In  some  makes  of  automobiles,  two  independent  means  of  igni- 
tion are  employed. 

Other  makes  of  automobiles  employ  the  high-tension  dis- 
tributor system  with  batteries  or  a  modification  of  this  system, 
such  as  the  Delco  or  the  Atwater  Kent  system. 

Fig.  149  illustrates  an  ignition  system  for  a  four-cylinder  auto- 
mobile engine  which  uses  battery  with  master  vibrator.  The 
master  vibrator,  as  previously  explained,  eliminates  the  neces- 
sity of  adjusting  the  vibrators  of  four  different  coils,  the  master 
vibrator  serving  for  all  the  cylinders. 

The  disadvantages  of  the  master-vibrator  system  result  from 
the  fact  that  a  faulty  adjustment  of  this  vibrator,  which  serves 
all  the  coils,  will  throw  the  entire  system  out  of  order.  With 


150 


FARM  MOTORS 


Non-Vibrcxtina  Induction  Co/ Is 


$_] 

FIG.  149. — Ignition  system  with  battery  and  master  vibrator. 


J j j 

FIG.  150. — High-tension  distributor  system. 


AUTOMOBILES  151 

vibrators  on  each  of  the  coils,  an  imperfect  adjustment  of  one 
vibrator,  while  decreasing  the  power  of  the  engine,  will  not  dis- 
turb the  entire  system. 

In  some  automobiles  the  high-tension  distributor  system,  often 
called  the  synchronous  ignition  system,  is  used.  This  requires 
only  one  induction  coil  for  all  the  cylinders.  This  system  must 
be  provided  with  an  interrupter  for  the  primary  circuit  and  with 
a  distributor  to  direct  the  discharge  of  the  single  coil  to  the  spark 
plug  of  the  several  cylinders  in  rotation.  The  distributor  and 
the  interrupter  are  mounted  together.  The  various  parts  of 
the  high-tension  distributor  system  are  illustrated  and  named  in 
Fig.  150. 

The  Atwater  Kent  system  is  of  the  high-tension  distributor 
type  and  operates  with  a  primary  or  storage  battery  (Chapter  X) . 
The  essential  parts  of  the  Atwate*  Kent  system  (Figs.  151,  152, 
153)  are: 

1.  A  non- vibrator  type  of  induction  coil  with  primary  winding, 
secondary  winding,  and  electric  condenser.     This  type  of  induc- 
tion coil  produces  only  a  single  spark  as  the  circuit  is  made  and 
broken  only  once. 

2.  A  timer  or  contact-maker  in  the  primary  circuit.     The 
timer  is  constructed  so  that  the  length  of  contact  is  independent 
of  the  engine  speed. 

3.  A  high-tension  distributor  with  as    many    contact    points 
as  there  are  cylinders. 

4.  A  governor  which  advances  the  spark  as  the  speed  increases. 
This  feature  of  the  Atwater  Kent  system  eliminates  the  necessity 
of  the  spark  control  lever  on -the  steering  wheel;  and  the  driver 
has  to  control  only  the  carburetor  throttle.     The  automatic 
spark-advance  mechanism,  the  circuit-breaker  or  contact-maker, 
and  the  distributor  are  all  carried  by  one  vertical  shaft.     The 
point  of  ignition  can  also  be  hand-controlled  by  turning  a  sleeve 
beneath  the  timer. 

The  Atwater  Kent  system  works  on  the  open-circuit  principle, 
similar  to  that  of  door  bells,  and  there  is  no  danger  of  running 
down  the  batteries  by  leaving  a  switch  closed. 

The  Delco  system  is  illustrated  in  Fig.  154.  This  system  in- 
cludes starting,  ignition,  and  lighting  systems  all  combined  in 
one.  A  motor-generator  set  performs  the  function  of  cranking 


152 


FARM  MOTORS 


DISTRIBUTOR 


•«*"'• 

MM ^ 


COIL 


CONTACT  MAKCP 


FIG.  151.— Wiring  diagram  of  the  Atwater  Kent  system. 


FIG.  152.— Contact  maker  of  the  Atwater  Kent  system. 


FIG.  153. — Atwater  Kent  unisparker. 


AUTOMOBILES 


153 


the  engine  and  of  supplying  electrical  current  for  ignition,  lighting, 
blowing  the  horn,  and  charging  the  storage  battery.  The  motor- 
generator  consists  of  a  dynamo  (Chapter  X)  with  two  field 
windings,  and  two  windings  on  the  armature  with  two  commuta- 
tors and  corresponding  sets  of  brushes.  This  construction  is 


made  in  order  that  the  machine  may  work. both  as  a  starting 
motor  and  as  a  generator.  The  ignition  apparatus  is  incor- 
porated in  the  forward  end  of  the  motor-generator.  A  combina- 
tion switch  is  used  for  the  purpose  of  controlling  the  lights,  the 
ignition,  and  the  circuit  between  the  electrical  generator  and  the 
storage  battery. 


154  FARM  MOTORS 

For  ignition  the  Delco  system  employs  a  non-vibrator  type  of 
induction  coil  with  a  timer  in  the  primary  circuit,  and  a  dis- 
tributor. A  governor  for  automatic  spark  advance  similar  to  that 
of  the  Atwater  Kent,  but  of  different  design,  is  employed. 

In  Fig.  154,  if  button  B  is  pulled  out,  the  current  for  ignition  will 
be  supplied  by  the  dry  cells.  By  pulling  button  M,  current  will 
be  supplied  through  wire  A,  if  the  generator  is  in  operation,  or  by 
the  storage  battery  through  wire  B. 

Automobile  Lubrication. — The  parts  requiring  lubrication  are 
the  main  shaft  bearings,  crankpin  bearings,  wristpin  bearings, 
camshaft  bearings,  timing  gears,  cams,  cam-lifter  guides,  cylinder 
walls  and  all  other  moving  parts,  such  as  the  yokes  and  ends  of 
rods,  and  steering  mechanism. 

Transmission  gears,  differential,  and  axle  bearings  are  lubri- 
cated with  heavy  grease,  as  these  parts  and  their  casings  are  not 
oil-tight.  In  cold  weather  it  may  be  necessary  to  thin  down  the 
lubricant  of  the  transmission,  the  differential  and  the  rear  axle. 
Wheel  bearings  should  be  packed  with  thin  cup  grease. 

Occasional  oiling  of  the  clutch  will  insure  free  shifting  of  the 
transmission  gears.  An  engine  oil  mixed  with  graphite  is  often 
used  for  this  purpose. 

The  lubrication  of  the  steering  mechanism  should  receive 
careful  attention.  The  worm  housing  should  always  be  packed 
full  of  grease. 

Ball  bearings  and  magnetos  should  be  lubricated  with  vaseline. 

In  several  of  the  light  automobiles  the  splash  system  of  lubri- 
cation is  employed.  The  lubricating  oil  is  supplied  to  the 
crank  case  of  the  motor.  The  connecting  rods  dip  into  and 
splash  the  oil  to  the  various  parts  of  the  engine. 

A  combination  of  the  splash  constant-level  system  and  force 
pump  (Fig.  109,  Chapter  V)  is  used  to  a  considerable  extent. 
The  circulating  pump  lifts  the  oil  from  a  reservoir  or  pump  below 
the  main  crank-case  bottom.  The  oil  passes  through  a  sight 
feed  or  sight  glass  on  the  dash,  so  that  the  circulation  can  be 
observed  by  the  driver,  and  to  the  various  bearings.  From  the 
bearings  the  oil  falls  to  the  reservoir  at  the  bottom  of  the  crank 
case.  The  height  of  the  oil  in  the  crank  case  is  such  that  the 
connecting  rods  give  additional  lubrication  by  splash. 

The  selection  of  a  high-grade  lubricating  oil  is  of  great  impor- 


AUTOMOBILES  155 

tance,  if  good  service  and  low  cost  of  automobile  maintenance 
are  desired.  The  oil  charts  in  the  manufacturer's  instruction 
book  (Fig.  155)  should  be  carefully  followed  and  the  parts  should 
be  lubricated  at  the  intervals  indicated.  The  oil  best  suited 
for  the  various  parts  usually  has  been  determined  by  automobile 
manufacturers,  and  their  recommendations  should  be  followed 
for  the  various  makes  of  cars. 

If  the  lubricating  oil  is  too  light  in  body  or  if  the  piston  rings 
are  leaky,  the  oil  will  work  into  the  combustion  chamber,  pro- 
ducing not  only  a  loss  of  oil,  but  also  carbon  deposits  on  valves, 
cylinder  walls,  and  spark  plugs. 

An  oil  which  is  too  heavy  will  not  spread  freely,  and  poor 
lubrication  will  result. 

Insufficient  lubrication  will  be  indicated  by  the  overheating 
of  the  parts  and  by  a  metallic  knock,  and  will  result  in  cutting, 
scratching,  twisting,  or  otherwise  ruining  the  parts. 

An  excess  of  oil  is  usually  more  harmful  to  the  motor  cylinder 
than  to  the  other  parts,  where  the  burnt  oil  will  cause  carbon 
deposits.  Too  much  cylinder  lubrication  is  indicated  usually 
by  a  bluish,  smoky  exhaust,  but  a  clear  exhaust  is  not  always  an 
indication  that  the  motor  is  properly  lubricated. 

Carbon  deposits  will  result  in  preignition,  sticky  pistons, 
sticky  valves,  dirty  spark  plugs,  and  ultimate  loss  of  efficiency. 
Too  much  lubrication  of  transmission,  differential,  or  bearings 
will  produce  waste  by  the  leaking  of  the  lubricant  at  the  joints. 

Automobile  Starting  Systems. — Automobile  motors  are  started 
by  hand-cranking  or  by  some  automatic  starting  device.  Before 
the  motor  is  cranked,  the  carburetor  throttle  lever  on  the  steering 
wheel  should  be  moved  up  to  open  the  throttle.  The  spark 
lever  should  be  shifted  to  the  retard  position,  as  failure  to  do 
this  may  result  in  the  engine  kicking  back  on  account  of  back- 
firing. The  gears  should  be  thrown  into  neutral  position  (Fig. 
136). 

In  cranking  by  hand,  the  crank-handle  latch  should  be  thrown 
back  in  order  to  free  the  crank.  The  crank  should  now  be  pushed 
in  as  far  as  possible  and  turned  in  the  clockwise  direction  until  it 
catches.  The  motor  should  start  if  the  crank  is  given  a  quarter 
or  a  half  turn  in  the  right-hand  direction.  In  cranking  an  engine, 
always  set  the  crank  so  as  to  pull  up.  One  should  not  bear 


156 


FARM  MOTORS 


FIG.  155. — Lubrication  chart. 
(For  description  see  page  157.) 


AUTOMOBILES  157 


DESCRIPTION  OF  FIG.  155. 

1.  Every  500  miles  grease  spring  hanger,  cup  grease. 

2.  Every  500  miles  grease  motor  trunion,  cup  grease. 

3.  Every  2000  miles  remove  front  wheels  and  repack  roller  bearings  with 
cup  grease. 

4.  Always  keep  motor  oil  reservoir  well  supplied  with  motor  oil. 

5.  Inspect  the  gauge. 

6.  Every  500  miles  grease  spring  shackles,  cup  grease. 

7.  Every  500  miles  grease  drag  link,  both  ends,  cup  grease. 

8.  Every  500  miles  grease  steering  gear  crank,  cup  grease. 

9.  Every  3000  miles  remove  plug  in  steering  gear  and  fill  with  cup  grease. 

10.  Every  300  miles  oil  brake  and  clutch  shaft,  motor  oil. 

11.  Every  1000  miles  fill  universal  joint,  cup  grease. 

12.  Every  500  miles  grease  spring  shackle,  cup  grease. 

13.  Every  300  miles  oil  brake  equalizer  shaft,  motor  oil. 

14.  Every  1000  miles  fill  universal  joint,  cup  grease. 

15.  Every  500  miles  grease  spring  seat  bearing,  cup  grease. 

16.  Every  500  miles  grease  rear  axle  outer  bearing,  cup  grease. 

17.  Occasionally  fill  differential  case,  use  transmission  oil. 

18.  Every  500  miles  grease  spring  hanger,  cup  grease. 

19.  Every  200  miles  oil  fan  shaft,  motor  oil. 

20.  Every  300  miles  grease  king  bolt,  cup  grease. 

21.  Every  500  miles  grease  spring  shackles,  cup  grease. 

22.  Every  500  miles  oil  spark  advance  governor,  above  and  below,  motor 
oil: 

23.  Every  300  miles  oil  generator  bearings,  front  and  rear,  five  drops 
motor  oil. 

24.  Every  300  miles  grease  starter  gear  bearing,  cup  grease. 

25.  Every  500  miles  grease  speedometer  swivel  joint,  cup  grease. 

26.  Every  500  miles  inspect  and  fill  to  top  of  jack  shaft,  transmission  oil. 

27.  Every  500  miles  grease  spring  shackles,  cup  grease. 

28.  Every  500  miles  grease  torque  hanger,  cup  grease. 

29.  Every  500  miles  grease  front  bearing,  cup  grease. 

30.  Every  500  miles  grease  torque  hinge,  cup  grease. 

31.  Every  500  miles  grease  rear  axle  outer  bearing,  cup  grease. 

32.  Every  500  miles  grease  spring  seat  bearing,  cup  grease. 


158 


FARM  MOTORS 


down  on  the  crank.  If  the  motor  does  not  start  after  this  is 
repeated  three  or  four  times,  the  cause  of  trouble  should  be 
determined  before  further  cranking. 

Electric  automatic  starting  devices  are  usually  employed  in 
modern  automobiles.  An  electric  self-starter  consists  of  an 
electric  generator  for  furnishing  electricity,  a  storage  battery,  and 
an  electric  motor  to  crank  the  automobile  engine.  The  electric 
starting  system  is  also  supplied  with  switches  for  the  purpose  of 
controlling  the  supply  of  current;  with  protective  devices  such 
as  fuses  or  circuit-breakers  to  prevent  the  discharging  of  the 


JTINQ  PEDAL. 


FIG.  156. — Delco  starting  system. 

storage  battery  or  damage  to  coils,  motor,  or  lamps;  with  an 
electric  regulator  to  maintain  constant  voltage  for  various  speeds 
of  engine,  and  with  electric  meters  for  the  purpose  of  indicating 
the  amount  of  current  supplied  by  the  generator  to  the  storage 
battery,  and  for  indicating  how  much  current  is  being  supplied 
by  the  battery  for  ignition,  lighting,  and  starting. 

Electric  starters  are  built  in  connection  with  the  single-unit, 
the  two-unit,  or  the  three-unit  system.  In  the  single-unit  system 
electric  generator  and  motor  are  in  one  unit  and  this  motor- 
generator  is  used  for  cranking  the  engine,  for  charging  the  storage 
battery,  and  for  furnishing  current  to  be  used  for  operating  the 
engine  ignition  system  and  for  the  automobile  lights.  In  the  two- 
unit  system  a  separate  motor  which  receives  its  current  supply 
from  a  storage  battery  is  used  for  cranking  the  engine.  The 


AUTOMOBILES  159 

electric  generator  supplies  current  for  charging  the  storage  battery 
and  also  for  ignition  and  lighting.  In  the  three-unit  system  a 
magneto  furnishes  current  for  the  engine  ignition  system;  a 
separate  direct -current  motor,  supplied  with  current  from  a 
storage  battery,  is  used  for  cranking;  while  the  electrical  generator 
is  used  only  for  charging  the  storage  battery  and  for  operating 
the  lights. 

There  are  a  large  number  of  electric  self-starters  on  the  market. 
Only  two  types  will  be  described  in  this  chapter  in  order  to 
illustrate  the  fundamental  details. 

The  Delco  system  (Figs.  154  and  156)  combines  in  one  unit 
the  starting  motor,  the  electrical  generator,  and  the  ignition 


FIG.  157. — Three-unit  starting  system. 

system.  The  motor-generator  of  this  system  has  been  described 
in  connection  with  automobile  ignition.  This  motor-generator 
has  the  ignition  apparatus  in  the  forward  end  and  is  located  on  the 
right  side  of  the  engine. 

The  arrangement  of  the  various  parts  of  a  three-unit  starting 
system  is  illustrated  in  Fig.  157.  G  is  the  electric  generator,  M 
is  the  starting  motor,  and  I  is  the  magneto  for  ignition.  The 
starting,  lighting  and  ignition  features  operate  independently  of 
each  other. 

Mechanical  starters  are  also  used  to  a  limited  extent  on  small 
cars,  but  have  been  largely  superseded  by  electric  starters.  Some 
mechanical  starters  utilize  springs,  which  when  released  revolve 
the  engine  crankshaft.  Other  mechanical  starters  depend  for 
their  action  upon  a  clamp,  and  are  mainly  hand-cranking  devices 


160  FARM  MOTORS 

with  the  driver  remaining  in  his  seat.  In  general,  no  mechanical 
starter  will  start  an  engine  which  cannot  be  started  by  hand. 

Automobile  Lighting  and  Accessories. — Automobiles  are 
lighted  by  kerosene,  acetylene,  or  electricity.  Electricity  is 
coming  into  general  use.  Kerosene,  when  used,  is  placed  in  a 
side  light  or  a  tail  lamp. 

Acetylene  gas  is  generated  by  adding  water  to  calcium  carbide. 
The  gas  may  be  generated  while  the  car  is  in  operation,  or  may  be 
bought  in  the  compressed  form  in  steel  storage  tanks  under  the 
name  of  prestolite.  Prestolite  gas  is  more  commonly  used.  When 
the  storage  tank  is  exhausted,  it  is  exchanged  for  a  fully  charged 
tank.  Prestolite  tanks  are  usually  placed  on  the  running  board 
of  the  car.  The  acetylene  gas  may  be  lighted  by  a  match  or  by 
an  electric  spark  controlled  from  the  seat  of  the  operator. 

Electric  lights  are  most  popular.  Electricity  for  illumination 
is  usually  secured  from  a  storage  battery.  In  the  cars  with 
electric  starters,  the  storage  battery  is  recharged  from  the  gen- 
erator; in  other  cases  the  battery  is  recharged  from  an  outside 
source.  In  some  automobiles  alternating-current  magnetos 
furnish  lighting  current  while  the  car  is  in  motion. 

A  car  lighted  with  a  battery  charged  from  an  outside  source  is 
equipped  with  a  storage  battery  of  80  to  100  amp.-hr.  capacity 
(Chapter  X)  which  supplies  current  for  illumination  and  for 
blowing  the  horn.  This  lighting  storage  battery  is  usually  not 
used  for  engine  ignition,  unless  the  car  is  equipped  with  a  dynamo 
to  recharge  the  battery.  When  the  storage  battery  is  used  for 
lighting,  ignition,  and  starting  its  capacity  should  be  at  least 
90  amp.-hr. 

The  accessories  of  a  modern  automobile  are:  lamps,  speed- 
ometer for  measuring  the  speed  of  the  car  in  miles  per  hour,  horn, 
tool  kit,  jack,  tire  tools  and  tire  repairs,  gasoline  gage  on  dash, 
and  mirror. 

Management  of  Automobiles. — Before  an  attempt  is  made  to 
start  an  automobile,  the  operator  should  be  certain  that  the  fuel 
tank  has  sufficient  gasoline,  that  the  gasoline  valve  from  the 
tank  to  the  carburetor  is  open,  that  the  lubricating  system  is  in 
good  working  order,  that  the  radiator  is  filled  with  clean  water, 
and  that  the  engine  ignition  system  is  working  properly.  In  the 
case  of  a  dual-ignition  system  the  switch  should  be  closed  on  the 


A  UTOMOBILES  161 

battery  side.  The  transmission  gears  should  be  thrown  into 
neutral  position  (Figs.  135  and  136),  and  the  emergency  brake 
should  be  set.  Before  cranking  the  engine,  the  spark  lever 
should  be  shifted  to  the  retard  position  and  the  carburetor 
throttle  lever  should  be  advanced. 

The  rules  given  in  the  discussion  of  starting  systems  should  be 
followed  in  starting  an  automobile  engine  by  hand-cranking. 
With  electric  self-starters,  the  starting  pedal  is  pushed  forward 
and  down  as  far  as  it  will  go  and  is  held  down  until  the  engine 
starts.  As  soon  as  the  engine  starts,  the  foot  should  be  removed 
from  the  starting  pedal. 

Easy  starting  may  be  obtained  by  throttling 'the  air  just  as  the 
engine  stops,  thus  leaving  a  rich  mixture  in  the  motor. 

In  extremely  cold  weather,  or  after  prolonged  standing  of  the 
car,  it  may  be  necessary  to  prime  the  carburetor  or  even  to  inject 
gasoline  into  each  of  the  priming  cups. 

When  the  engine  starts,  the  spark  lever  should  be  advanced. 
To  start  the  car,  the  emergency  brake  is  released,  the  clutch  is 
slowly  disengaged  while  the  transmission  gears  are  thrown  into 
slow  gear  forward,  and  the  foot  accelerator  and  spark  lever  are 
operated  to  take  care  of  the  increased  load  on  the  car. 

To  stop  an  automobile,  the  motor  is  slowed  down  by  removing 
the  foot  from  the  accelerator,  the  clutch  is  disengaged,  the  service 
brake  is  operated  so  that  the  car  comes  to  a  gradual  stop,  and  the 
transmission  gears  are  shifted  into  the  neutral  position. 

To  stop  quickly  the  operator  presses  on  both  foot  pedals, 
releasing  the  clutch  and  applying  the  service  brake,  while  apply- 
ing also  the  hand  emergency  brake. 

To  reverse,  the  car  is  stopped  by  throwing  the  clutch  out,  thus 
disengaging  the  motor  from  the  transmission;  then  the  reverse 
gear  is  shifted  and  the  clutch  is  thrown  in  slowly. 

In  changing  from  low  speed  to  intermediate  or  .to  high  speed, 
the  foot  accelerator  is  released,  the  clutch  is  thrown  out,  the 
gears  are  quickly  shifted,  the  clutch  is  thrown  in  mesh,  and  the 
foot  accelerator  is  adjusted  for  proper  operation. 

In  going  down  a  long,  steep  grade  the  foot  and  emergency 

brakes  should  be  used  alternately  in  order  to  equalize  the  wear  on 

the  brakes.     The  engine  is  also  used  sometimes  as  a  brake  when 

descending  steep  hills,  with  the  throttle  closed,  the  spark  off,  and, 

11 


162  FARM  MOTORS 

the  clutch  engaged.  The  car  runs  the  engine  against  compression, 
and  the  engine  acts  as  a  brake.  By  using  the  engine  in  this  man- 
ner, the  wear  on  the  brakes  is  lessened. 

The  low  speeds  are  used  in  starting,  in  driving  through  bad  or 
sandy  roads  and  in  climbing  steep  grades. 

To  increase  engine  speed  the  carburetor  throttle  should  be 
opened  by  the  throttle  lever  on  the  steering  wheel  or  by  the  foot 
accelerator  and  the  spark  advanced. 

In  operating  a  car  the  clutch  should  always  be  thrown  out 
before  changing  gears.  No  attempt  should  ever  be  made  to 
engage  the  reverse  gear  until  the  car  comes  to  a  full  stop.  When 
the  clutch  is  thrown  in,  the  motor  is  connected  to  the  propelling 
gear.  The  clutch  should  always  be  thrown  in  gradually  in  order 
that  the  motion  of  the  motor  shaft  may  be  transmitted  to  the 
drive  shaft  without  jarring.  If  the  clutch  is  thrown  in  suddenly, 
the  motor  may  stop  or  the  mechanism  of  the  car  may  be  injured. 
The  clutch  should  be  thrown  out  when  the  automobile  is  to  be 
slowed  down,  as  this  will  reduce  wear  on  the  brake  lining.  The 
clutch  should  also  be  used  for  stopping  the  car,  if  a  sudden  stop  is 
not  desired. 

Brakes  should  be  used  only  when  a  rather  quick  stop  is  to 
be  made.  When  using  the  brakes  the  operator  should  apply 
pressure  gradually;  otherwise  the  wheels  will  be  stopped  before 
the  forward  movement  of  the  car  and  this  will  result  in  excessive 
wear  on  the  tires. 

When  driving,  the  operator  should  keep  his  feet  removed 
from  the  clutch  and  brake  pedals,  as  otherwise  undue  wear  will 
be  thrown  on  the  clutch  and  brake-operating  mechanisms.  Care 
must  be  taken  also  in  automobiles  equipped  with  self-starters  not 
to  push 'the  starter  pedal  while  the  engine  is  running,  as  this  would 
injure  the  starting  gear. 

In  timing  the  valves  of  an  automobile  engine  it  is  necessary  to 
set  the  camshaft  of  only  one  cylinder,  as  all  the  cylinders  are 
driving  from  the  same  camshaft.  The  exact  timing  of  the  valves 
depends  on  the  engine.  For  automobile  motors,  the  exhaust 
valve  ordinarily  should  open  about  40°  before  the  end  of  the. power 
stroke,  should  remain  open  during  the  entire  exhaust  stroke,  and 
should  close  about  10°  after  the  beginning  of  the  suction  stroke. 
The  inlet  valve  should  open  about  the  time  the  exhaust  valve  closes, 


AUTOMOBILES  163 

should  remain  open  during  the  remainder  of  the  suction  stroke 
and  close  30°  to  40°  after  the  beginning  of  the  compression  stroke. 

In  cold  weather  all  water  from  jackets  and  circulating  system 
should  be  drained  by  opening  all  pet-cocks  on  cylinder  jacket, 
pump,  feed  lines,  and  radiator.  If  it  is  not  practical  to  drain  the 
engine,  some  non-freezing  jacket  solution  should  be  used.  Glyc- 
erine, water  and  alcohol,  or  alcohol  and  water  have  been  used 
successfully  for  non-freezing  solutions. 

The  more  common  automobile  troubles  and  their  remedies  are 
illustrated  in  Table  6. 

An  automobile  engine  will  smoke  if  too  much  lubricating  oil 
is  used,  if  the  lubricating  oil  is  of  poor  quality,  if  the  piston  rings 
are  worn  or  broken,  or  if  the  mixture  of  air  and  fuel  is  incorrect. 

Engine  hissing  may  be  produced  by  loose  or  broken  spark 
plugs,  by  leaving  relief  or  priming  cocks  open,  by  having  exhaust 
pipe  loosely  connected,  or  by  leaky  gaskets  or  intake  manifolds. 

Irregular  action  of  the  automobile  engine  may  be  due  to 
incorrect  fuel  mixture,  poor  wiring  such  as  defective  insulation  or 
defective  connections,  carbon  deposits,  poor  fuel,  or  defects  in 
carburetor,  magnetos,  spark  plugs,  or  mechanism. 

Misfiring  is  often  due  to  carbon  deposits  on  the  spark  plug. 

Overheating  of  the  engine  may  be  due  to  incorrect  valve  or 
spark  timing,  defective  water  circulation,  clogged  radiator,  or 
lack  of  proper  lubrication. 

Engine  knocks  are  due  to  rich  mixture,  too  much  spark 
advance,  carbon  deposits  in  the  cylinder,  loose  or  worn  bearings, 
loose  flywheel,  or  lack  of  lubrication. 

Gasoline  Motor  Cycles. — Motor  cycles  are  propelled  by  air- 
cooled  high-speed  vertical  gasoline  engines.  The  motor-cycle 
engines  operate  usually,  on  the  four-stroke  cycle  and  are  built  as 
single-cylinder,  twin-cylinder,  or  four-cylinder  types.  The 
single-  and  twin-cylinder  machines  are  most  popular  on  account  of 
the  low  first  cost.  The  V  twin  cylinder  is  often  used  on  account 
of  its  simplicity  and  lightness,  there  being  only  one  crank  and 
camshaft  for  both  cylinders. 

The  splash  system  of  lubrication  is  commonly  employed.  The 
lubricating  oil  must  be  carefully  selected,  as  the  average  tem- 
perature of  the  cylinder  walls  of  the  motor-cycle  engine  is 
higher  than  that  of  the  water-cooled  automobile  engine. 


164 


FARM  MOTORS 


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166  FARM  MOTORS 

The  jump-spark  ignition  system  with  magneto  is  employed. 
Float-feed  carburetors  of  the  automobile  type  are  used. 

The  speed  of  the  engine  is  regulated  by  the  spark  and  throttle 
control.  Gear  transmissions  are  used  to  a  very  limited  extent. 

Belt,  chain,  and  shaft  drives  are  used.  The  coaster  form  of 
brake  is  used  in  some  makes. 

Motor  cycles  are  started  by  the  pedal,  by  a  hand  crank,  or  by  a 
foot  lever. 

Some  motor  cycles  are  provided  with  a  clutch  to  free  the  engine 
from  the  propelling  mechanism  and  operate  on  two  speeds. 

Problems:  Chapter  VI 

1.  Compare  the  advantages  and  the  disadvantages  of  the  automobiles 
operated  by  gasoline  engines,  by  electric  motors,  and  by  steam  engines. 

2.  Name  the  essential  parts  of  a  gasoline  automobile. 

3.  What  are  the  advantages  of  a  twelve-cylinder  automobile  engine  as 
compared  with  a  four-cylinder  engine? 

4.  Why  are  the  cylinders  of  the  majority  of  automobiles  cast  enbloc? 

6.  Sketch  and  compare  the  tee-head,  ell-head,  and  valve-in-the-head 
types  of  motors. 

6.  Describe,  using  a  clear  sketch,  the  thermo-syphon  system  for  cooling 
automobile  motors,  and  compare  this  with  the  forced-circulation  system. 

7.  Explain  the  action  of  the  sleeve-valve  type  of  motor. 

8.  Which  type  of  valve  is  most  commonly  used  in  automobile  motors? 

9.  Sketch  two  types  of  clutches  and  explain  how  they  work. 

10.  Sketch  and  explain  the  progressive  sliding-gear  transmission  system. 
Ill  Explain,  with  clear  sketches,  the  selective  sliding-gear  transmission 

system. 

12.  Using  Fig.  137  in  the  book  and  models,  if  available,  make  several 
views  of  the  planetary  system  of  transmission  and  explain  how  this  system 
works. 

13.  Make  a  clear  sketch  and  explain  the  friction  drive. 

14.  Compare  the  four  systems  of  transmission  as  to  advantages  and  dis- 
advantages. 

16.  Sketch  and  describe  some  form  of  differential  for  automobiles. 

16.  Show  by  means -of  sketches  what  is  meant  by  a  semi-floating  and  by  a 
full-floating  rear  axle. 

17.  Explain  by   means   of   sketches   the   steering    mechanism    of    an 
automobile. 

18.  What  are  the  functions  of  the  accelerator,  the  hand  levers  on  the  steer- 
ing wheel,  and  the  foot  pedals  of  the  automobile? 

19.  What  are  the  functions  of  the  service  brake  and  of  the  emergency 
brake? 


AUTOMOBILES  167 

20.  Explain  three  gasoline  feed  systems  for  automobiles. 

21.  What  is  the  function  of  a  master  vibrator  in  an  automobile  ignition 
system? 

22.  Make  a  clear  wiring  diagram  of   the  ignition  systems  for  a  four 
cylinder  automobile  engine,  using  batteries  with  a  master  vibrator  and  with 
four  non-vibrating  coils. 

23.  Explain  with  clear  sketches  and  diagrams  the  Atwater  Kent  ignition 
system. 

24.  Give  clear  sketch  showing  the  fundamental  parts  of  the  Delco  igni- 
tion system. 

26.  Compare  the  various  systems  used  for  automobile  ignition. 

26.  Which  parts  of  an  automobile  require  lubrication? 

27.  Why  should  the  lubrication  of  the  steering  wheel  receive  more  care- 
ful attention  than  that  of  any  other  part  of  an  automobile? 

28.  What  systems  of  lubrication  are  most  commonly  used  for  automobiles? 

29.  What  are  the  objections  to  a  lubricating  oil  which  is  too  heavy?  to  an 
oil  which  is  too  light? 

30.  What  are  the  resultsof  using  insufficient  lubricating  oil?    Of  using  too 
much  lubricating  oil? 

31.  Give  directions  for  starting  an  automobile  motor  by  hand-cranking. 

32.  Explain,  with  clear  sketches,  the  action  of  a  two-unit  electric  starter. 

33.  Give  directions  for  starting,  for   reversing,  for    stopping,   and  for 
operating  an  automobile. 

34.  Make  a  chart  showing  the  most  common  automobile  troubles  and 
their  remedies. 


CHAPTER  VII 
TRACTION  ENGINES 

Fundamental  Parts  of  a  Traction  Engine. — A  steam  or  a  gas 
engine,  explained  in  the  previous  chapters,  can  be  converted 
into  a  traction  engine  by  mounting  it  on  trucks  and  providing 
additional  mechanisms,  so  that  the  engine  not  only  will  be 
capable  of  producing  rotation  at  a  shaft,  but  also  will  move  itself 
over  fields  and  highways,  thus  performing  the  work  of  many 
horses  in  a  cheaper,  quicker  and  better  manner. 

All  traction  engines  must  consist  of  the  following  fundamental 
parts : 

1.  Power  Plant. — This,  in  the  case  of  steam  traction  engines, 
consists  of  a  steam  engine  and  boiler.     Gas  traction  engines 
employ  an  internal-combustion  engine  burning  gasoline,  kerosene, 
or  some  heavier  oil. 

Power-plant  accessories  include  valves  and  piping  from  boiler 
to  engine,  fuel  hopper,  water  tank,  safety  valve,  water  glass  and 
try-cock,  steam  gage,  blowoff,  pump  or  injector  or  both,  a  stack 
and  spark  arrester.  Some  steam  traction  engines  have  also  a 
feed-water  heater  which  heats  with  exhaust  steam  the  feed  water 
before  it  enters  the  boiler.  The  accessories  of  the  gas  traction- 
engine  power  plant  are  fuel  tanks,  water  tanks,  batteries  and 
battery  boxes,  magnetos,  carburetors,  cooling  systems. 

2.  Transmission  Mechanism. — The  speed  of  the  engine  is  too 
great  for  direct  utilization,  and  a  train  of  gears  must  be  inter- 
posed between  the  engine  and  drive  wheels. 

3.  Reversing    Mechanism.  —  Reversing    of    a    steam    traction 
engine  is  accomplished  either  by  a  link  similar  to  that  used  in 
locomotive  practice,  or  by  some  form  of  single  eccentric  radial 
valve  gear.     It  is  more  difficult  to  reverse  a  gas  traction  engine 
and  a  train  of  gears,  similar  to  that  of  an  automobile,  must  be 
employed. 

4.  Steering  Mechanism. 

168 


TRACTION  ENGINES  169 

5.  Differential  or  Compensating  Gear. — The  purpose  of  this  is 
to  allow  one  drive  wheel  to  revolve  independently  of  the  other, 
this  being  necessary  when  turning  corners,  as  is  the  case  with 
automobiles  (Chapter  VI). 

6.  Friction  clutch  for  disengaging  engine  from  propelling  gear, 
so  that  the  power  of  the  engine  can  be  utilized  for  the  driving  of 
separators  or  other  machinery. 

7.  Traction-engine   frames    for    supporting    the   power  plant, 
transmission  mechanism  and  other  parts  and  for  keeping  all 
parts  in  proper  alignment.      Structural-steel  I-beams,  angles  and 
channels   are  employed  for  frame  construction.     Cast  iron  is 
also  used  for  certain  parts. 

8.  Traction  or  drive  wheels  (Figs.   161  and  162),  which  must 
be  provided  with  lugs  to  give  them  a  firm  footing  on  the  ground, 
and  with  mud  shoes. 

9.  Front  Wheels. — These  are  made  smaller  and  lighter  than 
the  traction  .wheels,  and  are  provided  with  smooth  tires.     To 
prevent  skidding  the  front  wheels  are  built  with  a  rim  in  the 
center  (Fig.  170).     The  front  wheels  turn  upon  an  axle  which 
is  attached  to  a  ball  and  socket  joint,  or  to  some  similar  mechan- 
ism, so  as  to  allow  for  uneven  ground  and  also  to  facilitate 
steering. 

STEAM  TRACTION  ENGINES 

Boilers. — The  boiler  of  the  steam  traction  engine  is  internally 
fired.  Some  builders  utilize  the  return-flue  type  (Fig.  158), 
others  the  direct-flue  or  the  locomotive  type  (Fig.  159). 

Coal,  straw,  wood  and  crude  oil  are  used  as  fuels  for  traction 
engines.  In  some  states  lignite  is  used.  Some  builders  supply 
traction  engines  with  attachments  for  converting  them  from  coal- 
burners  into  oil-burners. 

When  using  straw  for  fuel,  the  furnace  is  modified  as  shown  in 
Fig.  160.  Slab  grates  are  then  substituted  for  the  ordinary  coal 
grates  and  the  straw  is  fed  through  a  chute  S.  A  hinged  trap 
T  is  provided  to  prevent  the  entrance  of  air  when  the  straw  is 
not  being  fed. 

To  maintain  the  proper  draft,  steam  traction  engines  are  pro- 
vided with  a  blower  through  which  live  steam  is  passed  into  the 


170 


FARM  MOTORS 


smoke  stack  when  starting.     When  the  engine  is  running  it 
exhausts  into  the  stack  through  an  exhaust  nozzle. 

In  some  makes  of  traction  engines,  the  boiler  is  mounted  upon 
the  truck  and  is  used  as  the  foundation  for  the  engine  (Fig.  161). 


FIG.  158. — Flue-type  boiler. 


Hand 
Hole       Brace 

\ 


RearDoor 
Head- 
firebox 
DoorHead 
Firedoor 


'"Front Draft  Opening 


FiG._159.j^7Locomotive-type  boiler. 

Other  types  (Fig.  162)  have  the  engine  mounted  under  the  boiler, 
the  frame  supporting  both  engine  and  boiler. 

Pumps. — Three  types  of  feed  pumps  are  used  on  steam  trac- 
tion engines:  the  independent  pump  which  is  similar  to  the  types 
illustrated  in  Chapter  III,  the  crosshead  pump  P  (Fig.  163), 


TRACTION  ENGINES 


171 


which  is  driven  from  the  engine  crosshead  C,  and  the  gear-driven 
pump  (Fig.  164).  As  in  the  case  of  stationary  engines,  two  inde- 
pendent methods  should  be  provided  for  feeding  water  into  a 
traction  engine  boiler,  using  either  two  pumps  or  an  injector  and 
a  pump. 

Feed-water  Heaters. — Feed-water  heaters  are  used  on  some 
traction  engines.  The  type  often  employed  is  illustrated  in 
Fig.  165.  The  feed  water  passes  around  the  tubes  and  the 
exhaust  steam  passes  through  the  tubes. 

Engine  Types. — The  type  of  engine  usually  employed  is  some 
simple  form  of  steam  engine  with  a  slide  valve  (Fig.  166).  Some 


FIG.  160. — Furnace  for  straw  fuel. 

traction  engines  have  double-cylinder  engines.  Compound 
engines  (Fig.  167)  are  also  used  to  some  extent. 

The  details  of  the  engines,  governors  and  accessories  do  not 
differ  from  those  described  in  Chapter  IV. 

Reversing  Mechanisms  for  Steam  Traction  Engines. — A  steam 
traction  engine  can  be  reversed  either  by  a  Stephenson  link 
similar  to  that  used  on  locomotives,  or  by  some  form  of  single- 
eccentric  radial  valve  gear. 

To  reverse  an  engine  by  means  of  the  Stephenson  link,  it 
must  be  provided  with  two  eccentrics,  each  being  connected  by 


172 


FARM  MOTORS 


1 


TRACTION  ENGINES 


173 


an  eccentric  rod  to  the  end  of  a  link.     A  block  connected  to  the 
valve  slides  along  a  groove  in  the  link. 


FIG.  162. — Undermounted  traction  engine. 


FIG.  163. — Cross-head  pump. 

AirChamk^fm  Cap  forVabe  Chamber 


I      V      ^  /*  ""Pump  Drive  Pimon  '  V 

EiyfonkSSV    &  QuadrantShelf- 

FIG.  164. — Gear-driven  pump. 


Suction 


This  type  of  reversing  link  as  applied  to  a  traction  engine  is 
illustrated  in  Fig.  168.     The  two  eccentrics  shown  at  E  are 


174 


FARM  MOTORS 


attached  to  the  curved  link  L  by  means  of  the  eccentric  rods  A 
and  B.  The  position  of  the  link  is  varied  by  the  reverse  lever 
through  the  reach  rod.  In  one  position  of  the  link  the  motion 
to  the  valve  is  given  by  one  eccentric,  driving  the  shaft  in  one 
direction.  This  direction  of  rotation  is  reversed  by  raising  the 


FIG.  165. — Feed-water  heater. 

link,  so  that  the  valve  receives  motion  from  the  other  eccentric. 
If  the  reverse  lever  is  moved  so  that  the  block  is  in  the  middle 
of  the  link,  the  motion  given  by  both  eccentrics  will  be  equal  and 
opposite,  and  the  valve  will  have  no  motion. 


FIG.  166. — Engine  for  traction  engines. 

Most  traction  engines  employ  a  single-eccentric  radial  valve 
gear  (Fig.  169).  This  reversing  gear  consists  of  an  eccentric 
fastened  on  the  crankshaft  with  an  eccentric  strap  which  has  an 
extended  arm,  pivoted  in  a  sliding  block.  The  block  slides  up  and 


TRACTION  ENGINES 


175 


down  in  a  guide  and  gives  motion  to  the  eccentric  rod,  which  is 
transmitted  to  the  valve  through  the  rocker  arm  and  valve  stem. 
The  block  guide  is  hung  on  a  trunnion  and  it  can  be  tilted  in  any 
direction  by  the  reverse  lever  acting  through  the  reach  rod.  The 


liveSteam-.  Steam  Chest  Cover 


SteamPlug., 


High-pressure 
•"  Exhaust 


Portionof 
"EngineFrame 


FIG.  167. — Compound  engine  for  traction  engines. 

angle  at  which  the  guide  is  set  determines  the  direction  in  which 
the  engine  is  to  run.  The  reverse  quadrant  is  usually  provided 
with  three  notches.  When  the  reverse  lever  is  in  the  central 


FIG.  168. — Stephenson  reversing  link. 

notch,  no  motion  is  given  by  the  sliding  block  to  the  valve  stem. 
In  the  position  shown,  the  block  sliding  up  and  down  in  the  block 
guide  moves  the  valve  in  one  direction.  Placing  the  reverse 
lever  in  the  notch  at  the  extreme  right  reverses  the  engine. 


176 


FARM  MOTORS 


Steering. — Steering  is  accomplished  by  turning  the  front  axle. 
This  is  done  by  chains  C  (Fig.  170)  which  wind  upon  a  spool. 
The  spool  is  operated  by  hand  through  a  worm  W  and  pinion  P 
(Fig.  170).  Another  method  is  to  operate  a  screw  by  the  worm 


..-Rocker   Exhaustfort 


Sliding  Block 

Eccentric, 
Strap 
Reverse 
Reach 

Rod 

Eccentric 


FIG.  169. — Radial  valve  gear. 

and  pinion,  the  screw  moving  a  nut  which  is  connected  by  a 
system  of  levers  to  the  front  axle.  Some  traction  engines  em- 
ploy steering  mechanisms  similar  to  those  of  automobiles  (Chap- 


.••  Reverse  Head 
or  B.'ock  Guide 

Reverse  Head  Bracket 


FIG.  170. — Traction  engine  illustrating  steering  mechanism. 

ter  VI).     Jn  large  traction  engines  steering  is  accomplished  by 
power  furnished  by  the  engine  through  a  friction  disc. 

Transmission  Systems  and  Differentials. — A  friction  clutch, 
the  function  of  which  is  to  disengage  the  engine  from  the  pro- 


TRACTION  ENGINES 


177 


pelling  gear,  is  illustrated  in  Fig.  171.  The  flywheel  W  is  fixed 
to  the  engine  shaft,  and,  when  used  as  a  belt  wheel,  it  is  not  con- 
nected to  the  arm  C,  and  thus  does  not  transmit  motion  to  the 
pinion  F  which  is  rigidly  connected  with  the  arms  C.  When  the 
clutch  is  thrown  in,  pressure  is  applied  at  E  which  rests  in  a  groove 
in  the  piece  D.  This  results  in  B  crowding  the  shoe  A  against 
the  inner  rim  of  the  flywheel.  The  friction  clutch  has  two  shoes 
made  of  wood  or  of  some  other  yielding  material  A A}  which  press 
against  the  inner  rim  of  the  flywheel  when  the  clutch  is  thrown 


.FIG.  171.— Clutch. 

in,  and  this  transmits  the  motion  of  the  engine  through  the  arms 
C  and  pinion  F  to  the  transmission.  Means  are  provided  for 
taking  up  the  wear  on  the  shoes  so  as  to  keep  the  clutch  effective 
at  all  times. 

The  transmission  mechanism  delivers  the  power  from  the 
engine  to  the  traction  wheels  which  must  revolve  slower  than  the 
engine  crankshaft.  The  transmission  system  of  a  steam  traction 
engine  is  very  simple  and  consists  of  a  train  of  spur  gears  (Fig. 
172).  The  gear  A  receives  motion  from  the  engine  and  delivers 
this  through  the  train  of  gears  to  the  gear  B,  which  is  connected 
to  the  traction  wheel. 

When  a  traction  engine  turns  a  corner,  the  drive  wheel  on  the 
12 


178 


FARM  MOTORS 


outside  of  the  curve  must  turn  faster  than  that  on  the  inside.     If 
the  two  drive  wheels  were  rigidly  connected,  one  would  have  to 


FIG.  172. — Traction-engine  gearing. 


FIG.  173.— Differential. 


skid  or  slip,  when  turning  a  corner,  and  this  would  throw  a  great 
strain  on  the  front  wheels  and  axles.    The  differential,  sometimes 


TRACTION  ENGINES 


179 


called  a  compensating  gear,  allows,  if  occasion  demands,  one 
drive  wheel  to  move  faster  than  the  other. 

In  principle  the  traction-engine  differential  is  similar  to  the 
automobile  differentials  (Figs.  141  and  142). 

The  differential  can  be  placed  between  the  two  drive  wheels 
on  the  rear  axle.  A  more  common  method  is  to  have  the 
differential  on  a  separate  shaft,  the  traction  wheels  being  driven 
from  that  shaft  by  means  of  pinions. 


FIG.  174.— Differential. 

The  principle  of  differentials  as  applied  to  steam  and  gas 
traction  engines  is  illustrated  in  Figs.  173  and  174.  The  differ- 
ential shaft  S  consists  of  two  parts,  each  being  connected  either 
directly  or  through  gears  to  the  drive  wheels.  Two  bevel 
gears  are  keyed  to  these  two  differential  shafts  and  engage 
several  bevel  pinions,  marked  B,  which  turn  freely  on  their 
respective  shafts.  The  power  from  the  engine  is  transmitted 
through  the  pinion  P  to  the  large  spur  gear  A.  When  the  engine 
is  going  ahead  on  a  level  road  and  both  drive  wheels  are  rotating 
at  the  same  speed,  the  two  bevel  gears  will  also  revolve  at  the 
same  speed  and  the  small  pinions  marked  B  will  remain  station- 
ary. In  turning  a  corner  or  in  meeting  some  obstruction,  if  the 


180  FARM  MOTORS 

drive  wheel  connected  to  one  bevel  gear  moves  slower  than  that- 
connected  to  the  other,  D,  the  pinions  B  will  revolve  on  the  bevel 
gear  D.  In  other  words,  the  difference  in  motion  between  the 
two  drive  wheels  is  compensated  for  by  the  revolution  of  the 
pinions  B. 

Another  traction-engine  differential,  as  applied  to  gas  traction 
engines,  is  shown  in  Fig.  175,  the  letters  designating  the  same 
parts  as  in  Figs.  173  and  174.  The  two  pinions  E  and  F  connect 
the  differential  with  the  two  drive  wheels.  W  is  a  brake  wheel. 


FIG.  175. — Gas  traction-engine  differential. 

GAS  TRACTION  ENGINES 

The  term  "gas  traction  engines"  is  applied  to  such  as  are 
propelled  by  internal-combustion  engines.  The  fuels  most  com- 
monly used  are  gasoline,  kerosene  and  the  heavier  oils. 

The  use  of  gas  traction  engines  has  been  increasing  much  more 
rapidly  than  that  of  steam  traction  engines.  The  reasons  for  this 
are  as  follows: 

1.  The  gas  traction  engine  is  made  in  many  special  designs 
suitable  for  various  uses. 

2.  The  steam  traction  engine  is  practical  only  in  large  powers, 
while  gas  traction  engines  are  built  in  sizes  capable  of  pulling  as 
few  as  two  plows  and  as  many  as  fourteen  plows.     This  also 
means  that  gas  traction  engines  sell  at  sufficiently  low  cost  to 


TRACTION  ENGINES 


181 


enable  the  fairly  small  farmer  to  use  this  form  of  mechanical 
power.  The  prices  of  gas  traction  engines  vary  from  $500  to 
$4,500. 


FIG.  176. — Single-cylinder  motor. 


FIG.   177. — Twin-cylinder  two-stroke  cycle  motor. 

3.  The  operator  of  the  steam  traction  engine  must  carry  a  tank 
wagon  with  water  and  a  bulky  fuel  supply.     This  necessarily 


182  FARM  MOTORS 

limits  the  amount  of  plowing  by  this  form  of  engine.  With  the 
gas  traction  engine  the  fuel  and  water  supply  occupy  little  space. 

4.  Considerable  time  must  be  consumed  in  getting  up  steam 
for  operating  a  steam  traction  engine. 

The  Gas  Traction-engine  Motor. — The  majority  of  gas 
traction  engines  employ  internal-combustion  motors  which 
operate  on  the  four-stroke  Otto  gas-engine  cycle.  The  motors  are 
either  vertical  or  horizontal  and  of  the  long-stroke  type  and  oper- 
ate at  moderate  speeds  as  compared  with  automobiles. 

The  vertical  motor  resembles  the  automobile  motor,  but  is 
usually  heavier.  The  cylinders  of  the  vertical  motor  are  cast 


FIG.  178. — Two-cylinder  opposed  motor. 

singly  (Fig.  122) ;  some  makers  cast  cylinders  in  pairs.  The  four- 
cylinder  en-bloc  type,  common  in  automobile  practice,  is  used 
to  a  limited  extent  for  traction  engines. 

The  horizontal  motor  is  more  difficult  to  lubricate  and  is  bound 
to  wear  more  rapidly  than  the  vertical  types. 

The  types  of  motors  used  are  single-cylinder  (Fig.  176),  twin- 
cylinder  (Fig.  177),  two-cylinder  opposed  (Fig.  178),  and  four- 
cylinder  (Fig.  179). 

The  single-cylinder  motor  (Fig.  176)  is  usually  of  the  long- 
stroke  heavy-duty  horizontal  type  and  has  a  heavy  flywheel. 

The  two-cylinder  traction  engine  is  built  as  a  twin-cylinder 


TRACTION  ENGINES 


183 


motor  with  cylinders  mounted  side  by  side,  at  one  side  of  the 
crankshaft  (Fig.  177),  or  as  a  two-cylinder  opposed  motor  (Fig. 
178)  with  two  cylinders  set  horizontally  on  the  opposite  sides  of 
the  crankshaft.  The  two-cylinder  opposed  motor  is  better  bal- 
anced and  can  be  operated  with  lighter  flywheels.  The  twin- 
cylinder  type  of  motor  (Fig.  177)  occupies  less  space  and  has  bet- 
ter carburetion. 

Multiple-cylinder  motors  are  more  commonly  used,  as  they 
are  lighter  than  the  single-cylinder  motor  for  the  same  power 


T 


FIG.  179. — Four-cylinder  traction-engine  motor. 

developed.  Increasing  the  number  of  cylinders  produces  also  a 
motor  which  has  a  more  uniform  turning  effort  at  the  crankshaft, 
the  power  impulses  taking  place  more  frequently. 

The  four-cylinder  vertical  motor  (Fig.  179)  is  the  most  common 
type  for  large  traction  engines.  The  cylinders  of  the  four-cylinder 
motor  are  usually  placed  so  that  the  crankshaft  is  parallel  to  the 
tractor  frame.  In  some  designs  the  motor  is  set  crosswise  of  the 
frame.  In  the  crosswise  arrangement  the  motor  drive  is  direct, 
in  the  other  method,  the  drive  to  the  transmission  is  through 


184 


FARM  MOTORS 


bevel  gears.  While  the  direct  drive  eliminates  the  use  of  a 
bevel  gear,  the  other  design  can  be  built  with  longer  bearings 
without  widening  the  frame.  The  length  of  the  bearing  is  an 
important  consideration  in  large  traction  engines. 

The  motor  crankshaft  has  two,  three,  or  five  main  bearings  and 
one  camshaft  usually  operates  all  the  valves.  The  valve  cam- 
shaft is  driven  from  the  motor  crankshaft  by  a  two-to-one  gear, 
as  is  the  case  in  stationary  and  automobile  engines. 


FIG.  180. — Traction-engine  cooling  system. 


•  Traction-engine  cylinders  are  made  of  cast  iron  and  are 
provided  with  jackets  for  liquid-cooling.  Air-cooled  motors  are 
not  practical  for  traction  engines. 

Water  is  usually  used  as  the  cooling  medium.  Heavy  oils  and 
the  various  anti-freezing  compounds,  such  as  glycerine,  alcohol 
and  water,  or  alcohol  and  water,  are  also  used  to  some  extent. 

A  forced  system  of  water  circulation  is  usually  employed  with  a 
rotary,  a  centrifugal,  or  a  plunger  pump.  In  the  rotary  pump  the 
water  is  circulated  by  revolving  gears  and  in  the  centrifugal 
pump  by  an  impeller  or  paddle  wheel.  The  rotary  or  centrifugal 
pumps  are  more  generally  used,  as  they  are  more  simple.  The 


TRACTION  ENGINES  185 

thermo-syphon  system  of  water  circulation  (Fig.  125)  is  used  in 
some  makes  of  traction  engines. 

Some  form  of  radiator  (Figs.  180,  181)  is  employed  which  acts 
as  a  water  tank  and  cooler.  In  most  traction  engines  the  radia- 
tors are  similar  to  those  of  automobiles  but  heavier;  a  cooling  fan 
is  used  to  circulate  the  air  through  the  radiator.  The  exhaust 
gases  are  also  utilized  in  some  designs  to  aid  in  the  circulation  of 
the  air. 

The  poppet  type  of  valve  (Fig.  127)  is  always  employed. 
Valves  are  constructed  of  a  nickel-steel  or  cast-iron  head,  and 
a  carbon-steel  stem,  stem  and  head  being  welded  together. 

The  valves  are  arranged,  as  in  automobiles  (Figs.  130,  131, 
132),  in  three  distinct  ways:  namely,  the  tee-head,  the  ell-head 
and  the  valve-in-the-head  construction.  With  the  tee-head  or 


FIG.  181.— A  small  gas  traction  engine. 

the  ell-head  construction  the  valve  seats  are  in  a  pocket  cast  on 
the  side  of  the  cylinder  proper,  which  forms  a  very  inefficient 
combustion  space.  The  valve-in-the-head  motor  has  a  very 
compact  combustion  chamber. 

In  the  valve-in-the-head  type  of  motor,  the  cylinder  head 
carrying  the  valves  is  a  separate  casting  (Fig.  182)  or  has  the 
valves  mounted  in  removable  cages  (Fig.  183). 

Many  makes  of  traction-engine  cylinders  are  built  with  remov- 
able heads  (Fig.  182).  When  the  cylinder  head  is  a  separate 
casting,  it  can  be  removed  easily  for  the  purpose  of  cleaning,  and 
the  valves,  with  this  form  of  construction,  can  be  more  thoroughly 
water-jacketed  than  when  mounted  in  cages. 

When  the  valves  are  placed  in  cages  (Fig.  183),  the  cage  con- 
tains a  seat  for  the  valve  and  a  guide  for  the  valve  stem. 


186 


FARM  MOTORS 


FIG.  182. — Traction-engine  cylinders  with  removable  heads. 


AIR 
PASSAGE 


Fia.  183. — Valves  in  cages. 


TRACTION  ENGINES  187 

The  exhaust  valve  seat  is  usually  water-jacketed  and  in  some 
designs  the  inlet  valve  seat  is  also  water-jacketed  in  order  to  keep 
down  the  temperature  of  the  incoming  mixture. 

Traction  engines  are  generally  constructed  with  mechanically 
operated  inlet  and  exhaust  valves. 

Some  gas  traction  engines  are  provided  with  an  auxiliary  ex- 
haust port.  yVith  this  construction  the  exhaust  gases  pass 
directly  into  the  exhaust  pipe,  removing  the  hottest  gases  from 
the  exhaust  valve  and  decreasing  the  pressure  at  the  time  the 


FIG.  184. — Throttling  governor.  ' 

exhaust  valve  opens.     This  feature  is  particularly  advantageous 
when  the  engine  is  operated  continuously  at  heavy  loads. 

Traction  engines  are  governed  by  the  hit-and-miss  or  by  the 
throttling  type  of  governor.  The  hit-and-miss  governor  is  not 
adapted  for  work  where  close  regulation  is  essential.  The  major- 
ity of  modern  gas  traction  engines  are  equipped  with  throttling 
governors.  The  throttling  governor  is  of  the  centrifugal  type 
and  controls  the  carburetor  throttle  (Fig.  184).  In  some  cases 
the  controlling  mechanism  is  arranged  so  that  the  governor  may 


188 


FARM  MOTORS 


be  cut  out,  and  the  carbureter  throttle  is  controlled  by  a  hand 
lever. 

The  speed  of  various  makes  of  traction-engine  motors  varies 
from  365  to  1,500  r.p.m.  The  majority  of  motors  operate  at 
speeds  of  500  to  750  r.p.m. 

The  belt  horsepower  of  various  makes  of  motors  varies  from 
10  to  120  h.p. 


Balanced 
Valve 


Valve  Chamber 

Stem       \f/>-  Valve 

~i~l    rH^  /•  Regulator 

\\^  JRj\\StrainerCup 

Admission  Manifold  - 
to  Cylinders 

FIG.  185. — Traction-engine  carburetor  and  governor. 

Carburetors  for  Traction  Engines. — Float-feed  carburetors  of 
the  single-jet  automobile  type  illustrated  in  Chapter  V  are  used. 
The  simpler  designs,  such  as  the  Kingston  (Fig.  78),  are  generally 
employed. 

The  arrangement  of  carburetor  and  throttling  governor  for 
one  form  of  traction  engine  is  illustrated  in  Fig.  185.  The  car- 
buretor is  of  the  concentric-float  type.  The  gasoline  passes 
through  a  strainer  before  entering  the  float  chamber.  The 


TRACTION  ENGINES 


189 


fuel  mixture  on  the  way  to  the  engine  cylinder  must  pass  through 
a  balanced  throttle  valve  which  is  under  the  control  of  the 
governor. 

To  burn  kerosene,  some  makes  employ  the  ordinary  float-feed 
carburetor,  which  has  a  jacketed  float  chamber  through  which 


FIG.  186. — Kerosene  carburetor. 

hot  water  passes.     The  kerosene  carburetor  illustrated  in  Fig- 
82  is  used  by  some  manufacturers. 

Another  form  of  kerosene  carburetor,  called  the  Secor-Higgins, 
is  illustrated  in  Fig.  186.  The  three  compartments  from  right 
to  left  are  for  gasoline,  water  and  kerosene.  The  lower  section 
is  the  mixing  chamber.  Gasoline  is  forced  into  the  mixing 


190 


FARM  MOTORS 


chamber  by  means  of  a  hand  pump.  Plunger  pumps  force 
water  and  kerosene  into  the  compartments.  The  air  enters 
through  air  intake  ports.  The  amount  of  air  entering  the  mixing 
chamber  is  controlled  by  the  governor.  The  throttle  opening 
which  admits  the  mixture  to  the  cylinder  is  also  under  the  con- 
trol of  the  governor. 

With  kerosene  fuel,  water  is  generally  mixed  with  the  air  and 
fuel  to  prevent  preignition.  Very  little  water  should  be  used  at 
light  loads,  and  the  quantity  of  water  injected  at  higher  loads 


Jo5park 


FIG.  187. — Wiring  diagram  for  four-cylinder  motor. 

should  be  sufficient  only  to  produce  proper  operating  conditions. 
With  heavier  liquid  fuels,  the  capacity  of  an  engine  of  the  same 
bore,  stroke  and  speed  is  increased  by  water  injection.  Water 
injection  also  reduces  the  amount  of  carbon  deposit,  but  produces 
a  slower  burning  mixture  with  the  consequent  poorer  fuel 
economy. 

The  majority  of  traction  engines  are  equipped  to  burn  kero- 
sene as  well  as  gasoline. 

Ignition  for  Gas  Traction  Engines. — Nearly  all  traction  engines 
operate  with  the  jump-spark  system  of  ignition  (Chapters  V  and 
VI).  .  The  jump-spark  system  is  more  simple  mechanically, 


TRACTION  ENGINES 


191 


having  fewer  parts  than  the  make-and-break  system.  The  ig- 
nition system  differs  from  that  used  in  automobiles  in  that 
magnetos  are  commonly  employed.  In  some  cases  the  dual 
system  is  employed,  in  which  the  motors  are  started  with  current 
supplied  from  a  dry  or  storage  battery,  but  operate  with  mag- 
netos. In  other  makes,  the  motor  is  started  on  the  magneto. 
The  present  tendency  seems  to  be  to  eliminate  the  battery  and 
to  use  the  magneto  for  starting. 

A  wiring  diagram  for  a  four-cylinder  traction  engine  is  illus- 
trated in  Fig.  187. 

The  make-and-break  system  of  ignition  is  used  to  a  limited 
extent  for  small  traction  engines  in  connection  with  a  slow-speed 


FIG.  188.— Clutch. 

single-cylinder  motor.  With  the  make-and-break  system  an 
oscillating  magneto  (Fig.  100)  is  often  employed. 

Transmission  Systems  and  Differentials. — The  clutch  of  the 
gas  traction  engine  has  the  same  function  as  that  of  the  auto- 
mobile and  connects  or  disconnects  the  motor  from  the  propelling 
gear.  The  types  of  clutches  used  for  gas  traction  engines  are 
similar  in  principle  to  those  illustrated  in  Figs.  133,  134  and 
171.  The  expan ding-cone,  expanding-shoe,  multiple-disc,  float- 
ing-plate and  clamp-plate  types  are  employed.  Usually  one  part 
of  the  clutch  is  part  of  the  flywheel.  A  traction-engine  clutch  is 
illustrated  in  Fig.  188. 

Some  traction  engines  are  constructed  with  a  single  reversing 


192 


FARM  MOTORS 


mechanism  and  without  speed-change  gears,  while  other  trac- 
tion engines  have  the  reversing  mechanism  incorporated  with 
the  speed-change  gears;  some  manufacturers  employ  a  reversing 
mechanism  which  is  separate  from  the  speed-changing  mechan- 
ism. The  highest  speed  in  the  case  of  traction  engines  is  usually 
obtained  through  gearing  instead  of  by  the  direct  motor  drive. 
The  reason  for  this  is  that  the  traction  engine  is  used  most  of  the 
time  for  plowing  or  for  other  heavy  work,  "which  requires  a  slow 
speed;  by  operating  the  direct  drive  at  the  slower  speeds  the 
heavy  work  can  be  accomplished  with  few  gears,  thus  increasing 
the  efficiency  of  the  drive. 


FIG.  189. — Traction-engine  transmission  system. 

One  simple  form  of  gas  traction-engine  gearing  is  illustrated 
in  Fig.  189.  The  differential  gear  used  in  connection  with  the 
engine  of  Fig.  189  is  of  the  spur-gear  type  similar  in  principle  to 
that  illustrated  in  Fig.  142, 

Another  simple  traction-engine  transmission  system  is  illus- 
trated in  Fig.  190. 

A  two-speed  transmission  system  is  shown  in  Fig.  191.  The 
reversing  mechanism  consists  of  two  bevel  pinions  (A,  B)  which 
are  driven  from  the  motor  shaft.  The  bevel  gears  A  and  B 


TRACTION  ENGINES 


193 


drive  the  differential  driving  gear  D  through  the  large  bevel  gear 
M.     In  the  neutral  position  these  bevel  gears  A  'and  B  revolve 


FIG.  190. — Traction-engine  transmission. 


FIG.  191. — Two-speed  transmission  system. 

freely.     The  lever  R  is  used  for  connecting  either  bevel  gear  A 
or  B  with  the  driving  shaft.     The  lever  S  controls  the  speed- 
is 


194 


FARM  MOTORS 


changing  gears  and  the  lever  C  is  for  the  clutch.  The  shaft  P 
is  for  the  belt  pulley. 

In  some  traction  engines  the  speed-changing  mechanism  is 
similar  to  that  used  in  automobiles.  The  type  generally  used 
is  the  selective-transmission  system  (Fig.  192). 

A  friction  drive  (Fig.  193)  is  employed  in  some  makes,  this 
drive  differing  from  the  automobile  friction  drive  in  that  the 
fibrous-covered  friction  wheel  is  mounted  on  the  engine  crank- 
shaft; in  automobiles  the  disc  is  the  driving  member. 

In  some  designs  clutches  are  used  for  reversing.  A  single 
lever  operates  two  clutches,  one  of  which  is  used  for  reversing. 


FIG.  192. — Selective  transmission  system. 

Differentials  for  gas  traction  engines  were  illustrated  and  de- 
scribed in  connection  with  Figs.  173,  174,  and  175.  Spur-gear 
differentials  similar  to  that  of  142  are  also  employed  in  some  gas 
traction  engines.  Some  of  the  light  traction  engines  dispense 
entirely  with  the  differential  and  use  only  one  traction  wheel. 

Type  of  Traction. — The  majority  of  traction  engines  use  the 
two  rear  wheels  as  the  traction  wheels  or  drive  wheels,  while  the 
two  front  wheels  are  for  steering.  Some  makes  use  a  traction 
drum,  several  are  constructed  so  that  the  front  wheels  are  the 
driving  wheels,  and  in  other  makes,  all  four  .wheels  drive.  In 
the  case  of  three-wheeled  traction  engines,  one  large  drum,  two 
front  wheels,  or  two  rear  wheels  are  used  for  driving. 

Traction  engines  are  also  built  on  the  "creeping-grip"  or 
"caterpillar"  principle  (Figs,  194,  195,  196),  which  employ  a 


TRACTION  ENGINES 


195 


crawler  instead  of  a  wheel  or  drum.  The  object  of  this  construc- 
tion is  to  have  the  traction  wheels  travel  over  a  continuous, 
metalic  track  approximating  as  nearly  as  possible  that  over  which 


FIG.  193. — Traction  engine  with  friction  drive. 

the  locomotive  travels.  The  creepers  or  tractor  shoes  run  in- 
side a  continuous  belt.  Power  from  the  motor  is  transmitted 
from  a  jackshaft  to  the  creeper  drive  wheels  by  a  chain  and 
sprocket  drive  on  either  side,  The  advantages  of  this  construe- 


196 


FARM  MOTORS 


tion  are  greater  gripping  surface  for  the  same  weight  and  better 
distribution  of  weight. 


FIG.  194. — Creeping-grip  tractor. 


FIG.  195. — Caterpillar  tractor. 

Uses  of  Traction  Engines. — Desire  on  the  part  of  farmers  to 
raise  large  crops  and  to  put  under  cultivation  great  areas  of  land 
created  a  demand  for  mechanical  power.  With  mechanical  power 


TRACTION  ENGINES 


197 


the  number  of  horsepower  under  the  control  of  one  man  be- 
comes unlimited,  if  the  man  controlling  the  mechanical  power  is 
willing  to  learn  the  simple  fundamental  processes  which  govern 


FIG.  196. — Track  of  crawler  type  tractor. 

the  conversion  of  fuel  into  mechanical  energy  as  well  as  ,the 
simple  laws  of  mechanics  which  enable  one  to  keep  machines 
and  mechanisms  in  adjustment  and  in  perfect  working  order. 
A  traction  engine  is  capable  of  doing  the  following  field  work: 


FIG.  197. — Plowing,  seeding  and  harrowing. 

Clearing  the  land :  tearing  out  hedges,  pulling  up  trees,  stumps 
and  stones. 

Preparing  the  seed  bed  and  seeding  with  the  operation  of 
plowing,  listing,  disking,  harrowing,  drilling,  seeding. 


198 


FARM  MOTORS 


FIG.  198. — Deep  plowing. 


FIG.  199. — Harvesting  with  steam  traction  engine. 


TRACTION  ENGINES 


199 


Harvesting  operations  such  as  mowing,  hay  loading,  hay  hoist- 
ing, and  drawing  binders  and  diggers. 


FIG.  200. — Harvesting  with  gas  traction  engine. 

With  a  traction  engine  the  processes  of  plowing,  seeding,  and 
harrowing  can  be  carried  on  in  one  operation  (Fig.  197).  Deeper 
and  more  uniform  plowing  (Fig.  198)  can  be  carried  on.  Harvest- 


FIG.  201. — Tractor  cultivator. 


ing  operations  with  steam  and  gas  traction  engines  are  illustrated 
in  Figs.  199  and  200. 

Some  designs  of  traction  engines  are  built  low  and  are  suitable 
for  orchard  cultivation. 


200  FARM  MOTORS 

Power  cultivators  are  being  placed  on  the  market  which  are 
suitable  for  cultivating  corn  and  other  rowed  crops.  One  form 
of  tractor  cultivator  is  illustrated  in  Fig.  201.  The  motor  of 
this  machine  is  placed  on  the  frame  near  the  front  and  is  a  four- 
cylinder  vertical  internal-combustion  motor  with  the  cylinders 
cast  enbloc  similar  to  automobiles.  One  of  the  special  features 
of  this  traction  engine  is  that  the  two  drive  wheels  are  operated 
separately  by  means  of  friction-drive  transmission.  The  mechan- 
ism is  so  arranged  that  one  wheel  can  be  held  stationary  while  the 
other  travels  forward  or  backward.  To  facilitate  turning  around 
at  the  end  of  a  row  of  corn,  in  order  to  go  up  in  the  next  row,  the 
operator  throws  out  the  gear  connection  in  the  steering  apparatus 


FIG.  202. — Hay-bailing  machine  driven  by  traction  engine. 

and  the  front  wheel  acts  as  a  caster.  Then,  by  operating  the 
rear  wheels,  the  machine  can  be  made  to  turn  completely  around. 
The  cultivator  gangs  are  operated  by  the  driver's  feet. 

The  traction  engine  is  suitable  for  heavy-belt  work,  such  as 
hay  baling  (Fig.  202),  corn  shelling,  pumping  water  for  irrigation 
and  for  other  purposes,  grinding  feed,  ensilage  cutting,  sawing 
wood,  threshing,  husking,  hulling,  shredding,  filling  silos,  crush- 
ing rock,  and  elevating  corn  and  grain. 

Traction  engines  can  be  used  for  hauling  grain  and  other 
farm  products  to  the  shipping  point  or  to  the  market;  for  haul- 
ing fertilizer  and  other  material  to  the  farm;  also  for  moving 
houses,  barns  and  other  structures. 

In  connection  with  road  work,  traction  engines  are  used  for 


TRACTION  ENGINES 


201 


pulling  graders  (Fig.  203),  scrapers,  road  plows,  drags,  and  other 
road  implements,  as  well  as  road  materials. 

Traction  engines  can  be  used  for  digging  irrigation  ditches  and 
for  filling  drainage  ditches. 

Development  of  the  Gas  Traction  Engine. — The  development 
of  the  gas  traction  engine  has  been  exactly  the  reverse  of  the 
automobile.  The  earlier  automobiles  were  small  and  light  in 
weight ;  the  early  gas  traction  engines  were  very  heavy,  develop- 
ing 60  to  100  hp.  on  the  belt.  At  the  present  time  traction 
engines  developing  5  to  15  hp.  on  the  drawbar  (10  to  30  b.  hp.), 
and  capable  of  pulling  three  or  four  14-in.  plows,  are  used  in 


FIG.  203. — Tractor  used  for  pulling  graders. 

great  numbers  in  the  corn  belt.  Large  steam  or  gas  traction 
engines  developing  40  to  60  drawbar  horsepower  and  capable 
of  handling  10  to  14  plows,  are  used  in  the  Northwest  and  in 
other  parts  where  large  areas  must  be  cultivated  and  farm  labor 
is  scarce.  The  tendency  seems  to  be  for  the  large  farmers  to 
invest  in  several  machines,  each  designed  for  a  special  purpose, 
than  to  buy  one  all-purpose  machine  capable  of  performing  all 
the  work  of  the  farm. 

Attachments  are  available  for  converting  an  automobile  into 
a  light  traction  engine,  capable  of  pulling  one  or  two  plows.  The 
rear  wheels  of  the  automobile  are  replaced  with  pinions  which 


202 


FARM  MOTORS 


mesh  with  gears  on  the  traction  wheels.  The  traction  wheels 
revolve  on  a  special  axle  at  a  speed  which  is  one-eighth  to  one- 
tenth  that  of  the  automobile  rear  axle. 

The  traction  engine  probably  will  not  replace  the  horse  for 
all  purposes  very  soon,  but  will  replace  many  horses,  on  large 
farms,  and  especially  in  connection  with  the  heavy  farm  work. 
The  traction  engine  is  a  concentrated  form  of  power  plant  which 
can  work  day  and  night,  is  not  affected  by  heat,  and  can  be  used 
to  advantage  a  large  portion  of  the  year. 

Economy  of  Gas  Traction  Engines. — The  cost  of  operating  a 
gas  tractor  depends  upon  many  varying  factors,  such  as  the  kind 
of  fuel  used,  the  cost  of  fuel,  the  cost  of  attendance,  the  character 
of  the  soil,  and  the  type  of  machine. 

Experiments  carried  on  during  1915-1916  in  the  engineering 
laboratories  of  the  Kansas  State  Agricultural  College  indicate 
that  the  fuel  consumption  in  pounds  per  brake  horsepower  per 
hour  is  very  nearly  the  same  for  gasoline  and  for  kerosene.  The 
fuel  consumption  per  brake  horsepower  per  hour  (average  of 
tests  on  12  different  traction  engines)  was  found  as  follows: 


Traction-engine  rating 

in  brake  horsepower.  . 

15  to  26 

26  to  51 

51  to  90 

Gasoline  consumption, 

pounds  per  horsepower 

Full  load  

0.855 

0  720 

0  73 

Half  load  

1.147 

0  893 

0  93 

Quarter  load 

1  853 

1  416 

1  47 

With  kerosene  at  10  cts.  per  gallon  and  gasoline  at  20  cts.  per 
gallon,  the  cost  of  gasoline  fuel  will  be  about  twice  that  of  kero- 
sene for  the  same  power  developed.  The  advantages  of  kero- 
sene fuel,  due  to  the  lower  cost,  are  offset  to  a  greater  or  less 
degree,  depending  upon  the  operator,  by  the  added  trouble  in 
handling  the  traction  engine.  The  life  of  the  motor  probably  will 
be  less  with  kerosene  fuel.  To  this  should  be  added  the  lower 
reliability  insurance  with  the  heavier  fuels.  In  some  work  done 
by  traction  engines  reliability  is  the  most  important  factor. 

Rating  of  Traction  Engines. — Two  ratings  are  usually  given 
to  traction  engines.  •  One  is  in  brake  or  belt  horsepower.  This 
means  the  actual  power  developed  at  the  shaft  of  the  engine, 


TRACTION  ENGINES  203 

which  can  be  utilized  for  driving  various  machines  by  means  of 
a  belt  drive. 

The  other  rating  is  in  tractive  or  drawbar  horsepower.  To 
obtain  the  tractive  horsepower  the  amount  of  power  lost  in  trans- 
mission to  the  drive  wheels  and  that  required  to  propel  the  trac- 
tion engine  must  be  subtracted  from  the  brake  horsepower  de- 
veloped at  the  shaft  of  the  engine. 

The  tractive  horsepower  depends  on  the  kind  of  transmission 
gearing  and  on  the  character  of  the  roads  over  which  the  traction 
engine  must  be  propelled.  It  is  equal  to  from  one-half  to  two- 
thirds  of  the  brake  horsepower.  As  an  illustration,  a  traction 
engine  equipped  with  a  40-hp.  engine  will  be  able  to  produce  only 
20  to  27  hp.  at  the  drawbar  under  ordinary  conditions. 

The  belt  horsepower  of  various  makes  varies  from  10  to  120 
hp.  and  the  drawbar  horsepower  from  5  to  60  hp. 

The  ratings  are  usually  expressed  as  8-16,  5-10,  or  40-80. 
These  ratings  mean  8  drawbar  horsepower  and  16  belt  horse- 
power, 5  drawbar  horsepower  and  10  belt  horsepower,  etc. 

The  relation  between  the  rating  and  number  of  14-in.  plows 
a  gas  traction  engine  will  pull  is  approximately  as  follows: 

Rating  Number  of  plows 

5-10  1  or  2 

8-16  2  or  3 

10-20  3 

12-25  3  or  4 

20-40  5  or  6 

30-60  8  or  10 


Gas  traction  engines  range  in  road  speed  from  1^4  to  10  miles 
per  hour.  The  average  road  speeds  are  2  to  3  miles  per  hour. 
The  furrow  speeds  in  miles  per  hour  vary  from  1  to  3J^.  The 
average  furrow  speed  is  not  greater  than  2  miles  per  hour. 

The  drawbar  pull  in  pounds,  of  a  traction  engine,  traveling 
at  a  rate  of  about  2  miles  per  hour,  is  approximately  180  times 
the  drawbar  horsepower. 

Operation  and  Care  of  Traction  Engines.  —  The  general  direc- 
tions given  regarding  the  care  of  stationary  steam  and  oil  en- 
gines apply  also  to  the  motors  of  steam  and  gas  traction  engines. 

The  wearing  surfaces  must  be  well-lubricated  or  they  will 
wear  out,  and  lost  motion  in  bearings  must  be  avoided  to  prevent 


204  FARM  MOTORS 

pounding  and  broken  crankshafts.  Many  of  the  traction-engine 
troubles  can  be  traced  to  inefficient  lubrication  or  to  the  use  of 
poor  lubricating  oil. 

Bearings  may  be  oiled  by  means  of  grease  cups  (Figs.  53,  54), 
or  by  sight-feed  lubricators  (Fig.  56).  Gears  are  lubricated  with 
grease  or  with  some  other  heavy  lubricant.  Transmission  grease 
is  generally  used  for  the  transmission.  In  some  cases  heavy 
steam-cylinder  oil  is  employed  for  the  same  purpose.  Cylinders 
for  steam  traction  engines  are  lubricated  with  heavy  steam- 
cylinder  oil  by  a  mechanically  driven  oil  pump  or  by  an  automatic 
sight-feed  steam  lubricator  (Fig.  57).  A  medium  gas-engine 
cylinder  oil  should  be  used  for  lubricating  gas  traction-engine 


,-r'Cup  Grease 


FIG.  204. — Traction-engine  lubrication  chart. 

cylinders.  A  lighter  gas-engine  cylinder  oil  should  be  used  in 
cold  than  in  warm  weather. 

A  combination  of  splash  and  forced-feed  oiling  system  is  often 
used  for  traction-engine  lubrication. 

The  instructions  furnished  by  the  manufacturer  regarding 
the  kind  of  oil  to  be  used  and  the  lubrication  of  the  various  parts 
should  be  carefully  followed.  A  lubrication  chart  for  one  make 
of  traction  engine  is  illustrated  in  Fig.  204.  The  bearings  of 
magnetos  require  frequent  attention.  A  high-grade  sewing 
machine  oil  should  be  used  for  this  purpose. 

All  reputable  manufacturers  test  their  traction  engines  before 
shipment  from  the  factory.  The  purchaser,  upon  receiving  a 
traction  engine,  should  carefully  examine  all  parts.  The  rail- 


TRACTION  ENGINES  205 

road  company  and  the  manufacturers  should  be  notified  at  once 
if  any  parts  are  damaged  or  missing. 

Before  attempting  to  start  the  engine,  it  should  be  gone  over 
carefully,  all  nuts  tightened,  bearings  properly  set,  lubricators 
filled,  and  clutch  adjusted  so  that  all  shoes  come  into  contact 
with  the  inside  of  the  wheel  at  the  same  time.  The  operator 
should  make  certain  that  the  engine  has  a  sufficient  supply  of 
fuel  and  water  and  that  the  lubrication  system  is  in  good  working 
order.  The  fuel  for  a  gas  traction  engine  should  be  strained.  A 
chamois  skin  strainer  is  best  for  gasoline  while  a  funnel  with  a 
fine  screen  will  be  satisfactory  for  kerosene  fuel.  A  strainer  will 
prevent  dirt  from  getting  into  the  carburetor  and  the  supply 
pipes  from  clogging. 

In  the  case  of  steam  traction  engines  the  boiler  is  filled  about 
two-thirds  full  of  water  and  the  fires  are  started  as  explained  in 
Chapter  III.  Upon  first  using  a  boiler  it  is  liable  to  foam,  espe- 
cially if  the  water  is  bad,  but  after  washing  the  boiler,  or  changing 
the  water  several  times,  the  oil  and  grease  on  the  boiler  plates 
are  removed.  Clear,  soft  water  should  be  used.  Care  should  be 
taken  not  to  use  water  which  contains  lime.  The  water  gage 
cocks  should  be  tried  often  and  the  water  level  should  not  be 
allowed  to  be  below  the  second  gage.  Before  the  feed-water 
pump  is  started  the  operator  should  make  certain  that  the  feed 
line  to  the  boiler  is  not  closed.  It  is  desirable  to  use  the  pump 
and  to  keep  the  injector  as  a  reserve  for  emergencies.  In 
simple  single-cylinder  traction  engines  the  safety  valve  is  set  at 
about  130  lb.,  in  compound  engines  at  160  Ib.  The  fire  should 
be  kept  thin.  The  operator  should  fire  frequently  and  lightly. 
In  operating  a  steam  traction  engine  on  the  road  care  must  be 
taken  not  to  allow  the  engine  to  remain  with  its  rear  end  elevated 
for  any  great  length  of  time,  as  this  may  result  in  the  overheating 
of  the  crown  sheet.  The  water  glass  must  be  blown  out  two  or 
three  times  each  day  and  the  safety  valve  should  be  kept  in  good 
working  order.  The  reverse  lever  should  be  kept  as  close  to  the 
center  notch  of  the  quadrant  as  possible  in  order  that  the  engine 
may  operate  at  its  best  economy.  When  running,  the  throttle 
should  be  wide  open  and  the  steam  supply  to  the  engine  should 
be  varied  entirely  by  the  reverse  lever.  The  fire  flues  of  the  boiler 


206  FARM  MOTORS 

should  be  cleaned  frequently,  as  the  cleaner  the  flues  the  less  fuel 
will  be  required  to  keep  up  steam. 

In  starting  a  gas  traction  engine,  the  operator  should  be  cer- 
tain that  the  change  gears  are  in  the  neutral  position  and  that  the 
clutch  is  disengaged.  In  the  case  of  a  dual-ignition  system  the 
switch  should  be  closed  on  the  battery  side.  The  spark  lever 
is  then  retarded  and  the  carburetor  throttle  is  opened  so  as  to 
admit  a  small  supply  of  fuel.  The  shutoff  valve  at  the  gasoline 
tank  is  opened,  the  cylinders  are  primed  through  the  priming 
cocks,  and  the  motor  is  cranked.  The  quicker  the  crank  is  turned 
the  easier  the  engine  will  start.  After  the  motor  starts,  the 
spark  lever  is  advanced.  Some  traction  engines  are  started  by 
means  of  small  auxiliary  gasoline  engines. 

To  put  the  traction  engine  in  motion  the  clutch  is  thrown  in 
gradually  after  the  lever  controlling  the  change  gears  has-been 
shifted  to  the  position  required.  In  stopping  a  traction  engine, 
the  carburetor  throttle  is  closed,  the  switch  is  opened,  the  clutch 
is  disengaged  and  the  change-speed  lever  is  placed  in  neutral. 
Failure  to  place  the  lever  controlling  the  change  gears  in  the 
neutral  position  will  start  the  tractor  if  the  clutch  is  disengaged. 
The  operator  never  should  try  to  reverse  a  traction  engine  without 
first  bringing  the  machine  to  a  stop.  The  operation  of  the  trac- 
tion engine  is  controlled  by  the  carburetor  throttle  lever. 

One  accustomed  to  driving  an  automobile  will  find  the  trac- 
tion-engine steering  mechanism  less  sensitive.  More  turns  of 
the  steering  wheel  will  be  necessary  on  account  of  the  slower  speed 
of  the  traction-engine  motor  and  the  lower  gear  ratio  of  the 
steering  gear. 

In  running  a  traction  engine  on  the  road,  the  operator  should 
keep  his  eyes  on  the  front  wheels  to  prevent  accidents.  In  case 
a  traction  engine  is  landed  in  a  hole,  it  can  be  pulled  out  by 
placing  chains,  boards,  or  straw  under  the  drive  wheels.  The 
same  advice  applies  when  the  engine  slips.  Before  crossing  a 
bridge  the  operator  should  ascertain  that  it  is  safe.  In  case  of 
doubt,  planks  should  be  placed  to  distribute  the  load. 

A  competent  operator  handles  a  traction  engine  slowly  and 
deliberately,  and  never  hesitates  to  stop,  if  something  goes 
wrong  with  any  part  of  the  engine. 

Overloading  a  traction  engine  is  a  serious  mistake. 


TRACTION  ENGINES  207 

A  traction  engine  should  be  kept  at  all  times  in  adjustment  and 
in  perfect  working  condition.  This  cannot  be  accomplished  un- 
less the  engine  is  housed  properly.  A  traction  engine  represents 
a  large  investment,  the  depreciation  of  which  can  be  greatly  re- 
duced if  the  housing  question  is  carefully  considered.  A  frame 
or  a  concrete  structure  should  be  provided  which  not  only  will 
house  the  traction  engine  but  will  leave  sufficient  space  for  a 
farm  workshop  where  ordinary  repairs  can  be  made. 

The  tractor  operator  should  do  his  repairing  systematically. 
At  the  completion  of  a  hard  season's  work  the  machine  should  be 
thoroughly  overhauled.  All  old  grease  and  oil  should  be  removed 
from  cylinders,  bearings  and  transmission  case.  All  parts  should 
be  cleaned  with  kerosene.  Bearings  should  be  examined,  and  ad- 
justed by  means  of  liners.  In  ordering  repairs  for  engines,  give 
description  or  sketch  of  the  part  as  well  as  the  number  and  letters 
found  on  the  parts  wanted.  The  number  and  size  of  the  engine 
also  should  be  stated. 

The  clutch  should  be  examined  frequently  for  worn  parts. 

It  is  well  to  have  on  hand  an  extra  clutch  lining,  a  set  of  piston 
rings,  an  extra  connecting  rod,  several  new  spark  plugs,  cotter 
pins,  belts,  and  nuts  of  various  sizes  and  such  other  small  repair 
parts  as  may  be  worn  out  or  lost  in  the  operation  of  the  engine. 

Valves  for  gas  traction  engines  should  seat  properly  and  should 
be  reground  if  indications  show  wear.  To  grind  the  valve  into 
its  seat  the  valve  spring  is  removed  and  the  valve  is  taken  out. 
Flour  emery  dust  and  oil,  or  fine  carborundum  valve-grinding 
paste  and  oil  is  placed  on  the  valve  seat.  By  using  a  brace 
holding  a  screw- driver  bit  in  the  slot  on  the  top  of  the  valve,  the 
valve  may  be  revolved  back  and  forth  on  the  seat  with  very 
little  effort.  It  is  best  to  place  a  light  spring  on  the  valve  stem 
so  that  the  valve  is  held  up  and  off  from  its  seat. 

The  time  of  opening  and  of  closing  of  the  valves  of  gas  trac- 
tion engines  depends  upon  the  speed  of  the  engine.  The  valves 
of  a  high-speed  engine  should  open  sooner  and  remain  open  longer 
than  those  of  a  slow-speed  motor.  Ordinarily,  the  exhaust 
valve  should  open  30°  to  50°  before  the  beginning  of  the  exhaust 
stroke  and  should  remain  open  4°  to  10°  after  the  completion  of 
that  stroke.  The  inlet  valve  should  open  5°  to  12°  after  the 


208  FARM  MOTORS 

beginning  of  the  suction  stroke  and  should  close  18°  to  25°  after 
the  completion  of  the  suction  stroke. 

The  common  sources  of  trouble  with  a  traction  engine  are 
due  to  the  incompetency  of  operators,  who  are  responsible  for 
poor  or  insufficient  lubrication,  dirty  fuel,  carbon  deposits,  poor 
fuel  economy  and  high  depreciation. 

When  it  is  desired  to  draw  a  number  of  machines  at  the  same 
time  by  means  of  a  traction  engine,  care  must  be  taken  that 
the  machines  are  properly  hitched  to  the  engine.  The  hitch 
required  for  plowing  is  very  simple.  A  hitch  for  three-disc 
harrows  is  illustrated  in  Fig.  205.  This  consists  essentially  of 
a  supplementary  drawbar  B  which  is  connected  to  the  main 
drawbar  by  the  chain  A. 


FIG.  205.— Hitch  for  three-disk  harrows. 

In  laying  by  the  engine  for  the  winter,  it  should  be  placed  under 
cover  and  be  protected  from  rain  and  snow.  It  is  well  to  remove 
pistons  from  the  cylinders  of  gas  traction  engines,  clean  all 
deposits  and  then  oil  pistons,  cylinders  and  valves  with  a  heavy 
oil.  Magnetos  and  batteries  should  always  be  removed  to  a  dry 
place.  All  parts  should  be  carefully  drained.  In  fact,  it  is  well 
to  remove  all  drain  cocks  so  as  to  prevent  any  water  from  remain- 
ing in  cylinders  and  tanks. 

The  success  of  a  traction  engine  depends  not  only  on  the 
operator  but  also  on  the  business  ability  of  the  owner.  The 
farmer  should  so  plan  his  work  that  the  traction  engine  is  used 
not  only  for  plowing,  but  for  many  other  kinds  of  work.  To 
secure  the  best  results  the  traction  engine  should  be  kept  busy 
most  of  the  year. 


TRACTION  ENGINES  209 


Problems:  Chapter  VII 

1.  Name  the  fundamental  parts  of  a  traction  engine. 

2.  What  types  of  boilers  are  commonly  used  on  steam  traction  engines. 
Sketch  one  type. 

3.  Describe,  using  clear  sketches,  two  types  of  pumps  used  for  feeding 
water  to  steam  traction-engine  boilers. 

4.  Sketch  and  explain  in  detail  two  types  of  reversing  mechanisms  for 
steam  traction  engines. 

6.  In  which  respect  does  the  steering  mechanism  for  a  traction  engine 
differ  from  that  for  an  automobile? 

6.  Sketch  and  explain  some  form  of  differential  for  traction  engines. 

7.  Why  does  the  steam  turned  into  the  stack  of  a  steam  traction  engine 
improve  the  draft?     Explain  in  detail. 

8.  To  which  types  of  traction  engines  does  the  term  "gas  traction  engine" 
refer?     Give  reasons  for  the  great  popularity  of  the  gas  traction  engine. 

9.  Explain  the  distinctive  features  of  gas  traction-engine  motors  and  com- 
pare the  traction-engine  motor  with  automobile  motors. 

10.  Explain  differences  in  construction  between  radiators  employed  for 
automobiles  and  for  traction  engines. 

11.  Show  by  means  of  clear  sketch  the  action  of  a  throttling  governor. 

12.  Sketch  and  explain  a  jacketed  float-feed  carburetor,  suitable  for  burn- 
ing kerosene. 

13.  Explain  with  clear  sketches,  a  kerosene  carburetor  suitable  for  traction 
engines. 

14.  Give  a  wiring  diagram  for  a  four-cylinder  traction  engine. 

16.  Explain,  using  clear  sketches,  two  different  types  of  transmission  sys- 
tems suitable  for  traction  engines. 

16.  Investigate  and  report  why  some  small  traction  engines  are  capable 
of  working  satisfactory  without  the  use  of  a  differential. 

17.  Explain  the  various  types  of  traction. 

18.  What  are  the  advantages  of  the  gas  traction  engines  which  utilize  a 
crawler  instead  of  a  wheel  or  drum? 

19.  What  type  of  field  work  and  of  belt  work  is  a  traction  engine  capable 
of  doing? 

20.  What  are  the  fundamental  parts  of  a  power  cultivator  and  in  which 
respect  does  this  differ  from  the  ordinary  traction  engine? 

21.  How  does  the  cost  compare  of  operating  a  traction  engine  with  gasoline 
and  with  kerosene  fuel. 

22.  A  farmer  invests  in  a  10-20-hp.  traction  engine  $1,000.     If  he  uses 
the  traction  engine  only  60  days  per  year,  calculate  the  approximate  cost  of 
this  form  of  power  per  year,  taking  into  consideration  interest  on  investment 
at  6  per  cent.,  depreciation  10  per  cent.,  taxes,  insurance,  repairs.     Com- 
pute this  upon  the  basis  of  the  market  price  for  gasoline  and  for  kerosene 
respectively. 

23.  What  is  the  relation  between  the  belt  horsepower  and  the  drawbar 
horsepower  of  a  traction  engine? 

14 


210  FARM  MOTORS 

24.  What  is  meant  by  the  traction  engine  rating  5-10? 

25.  What  determines  the  number  of  plows  that  can  be  pulled  by  a  trac- 
tion engine  of  a  given  rating? 

26.  What  precautions  must  be  taken  in  starting  and  in  operating  a  gas 
traction  engine? 

27.  Explain  in  detail  how  to  grind  a  gas-engine  valve. 

28.  Give  directions  for  setting  the  valves  of  a  gas  traction  engine. 

29.  Report  on  the  possibility  of  utilizing  the  ordinary  automobile  as  a 
traction  engine.     What  special  attachments  would  be  needed? 

30.  What  precautions  must  be  observed  in  laying  by  a  traction  engine  for 
the  winter? 


CHAPTER  VIII 
WATER  MOTORS 

A  water  motor  converts  the  energy  possessed  by  moving  or 
falling  water  into  useful  work. 

Determining  the  Power  of  Streams. — Before  explaining  the 
Various  commercial  types  of  water  motors,  the  method  of  deter- 
mining the  power  available  in  any  water  stream  will  be  given. 

The  power  available  in  any  stream  depends  on  the  head  of 
water  and  on  the  quantity  of  water  which  can  be  utilized  in  a 
water  motor. 

The  term  head  is  applied  to  the  fall  of  water  available.  The 
head  can  be  determined  most  readily  by  running  an  engineer's 
level  from  a  point  at  the  upper  line  of  water  flow  to  a  point  at 
the  lower  line  of  flow.  The  vertical  distance  between  the  two 
points  gives  the  head  of  the  stream. 

One  method  of  determining  the  quantity  of  water  available 
for  utilization  in  a  motor,  is  to  find  the  cross-sectional  area  of 
the  stream,  and  to  multiply  this  by  the  velocity  of  the  stream. 
The  cross-sectional  area  of  a  stream  can  be  obtained  by  multiply- 
ing the  average  depth  of  the  stream  by  its  width.  To  find  the 
velocity,  several  floats  are  dropped  into  the  water  at  a  place  where 
the  depth  and  width  is  uniform  for  some  distance,  noting  the 
number  of  seconds  it  takes  for  the  floats  to  pass  a  certain  dis- 
tance. Since  the  velocity  of  a  stream  is  greatest  at  the  center 
and  is  least  at  the  bottom  and  sides,  the  velocity  as  obtained 
by  floats  should  be  multiplied  by  0.80  to  obtain  the  average 
velocity. 

As  an  illustration,  the  average  width  of  a  stream  is  10  ft., 
its  average  depth  is  4  ft.,  and  the  velocity  of  the  water,  as  obtained 
by  floats,  is  30  ft.  per  minute.  If  the  head  of  the  water  is  10  ft., 
calculate  the  power  which  could  be  obtained  from  a  water 
motor,  assuming  the  various  losses  in  the  motor  as  30  per  cent, 
and  the  average  stream  velocity  0.80  of  the  float  velocity. 

211 


212 


FARM  MOTORS 


The  area  of  the  cross-section  of  the  stream  =  10  X  4  =  40  ft. 
The  quantity  of  water  available  per  second  is  equal  to 

40  X  M  X  0.80  =  16  cu.  ft. 

As  the  weight  of  a  cubic  foot  of  water  is  62.4  Ib.  at  ordinary 
temperatures,  the  weight  of  water  delivered  to  the  motor  per 
second  is 

62.4  X  16  =  998.4  Ib. 

The  work  done  by  the  water  is 

998.4  X  10  =  9,984  ft.-lb. 


FIG.  206. — Water  measurement  by  weir. 

One  horsepower  is  equal  to  33,000  ft.-lb.  per  minute,  or  550  ft.- 
lb.  per  second;  allowing  30  per  cent,  for  friction,  the  power 
available  is 

9,984(1  -  0.30) 


550 


12.7  hp. 


Another  method  for  finding  the  quantity  of  water  available 
in  a  stream,  called  the  weir-dam  method,  is  illustrated  in  Fig.  206. 
A  notch  is  cut  in  a  thick  board  placed  at  some  point  in  the 
stream. 

The  length  of  the  notch  should  be  less  than  two-thirds  the 


WATER  MOTORS  213 

width  of  the  board.  The  bottom  of  the  notch  is  called  the  crest 
of  the  weir,  and  the  depth  of  the  water  at  that  place  should 
be  more  than  three  times  the  depth  of  the  water  flowing  over 
the  weir.  The  crest  of  the  weir  should  be  perfectly  level  and 
should  be  beveled  on  the  downstream  side.  The  edges  of  the 
notch  should  be  beveled  also  on  the  same  side.  In  the 
stream  back  of  the  weir,  and  at  a  distance  somewhat  greater 
than  the  length  of  the  notch,  a  stake  is  driven  level  with  the 
bottom  of  the  notch  or  crest  of  the  weir.  When  the  water  is 
flowing  over  the  weir,  measure  the  height  of  water  above  the 
top  of  the  stake.  If  this  height  in  feet  is  called  H  and  the  width 
of  the  notch  in  feet  B,  the  quantity  of  water  Q  flowing  through 
the  stream,  in  cubic  feet  per  second,  can  be  determined  by  the 
formula:  . 

Q  =  3.33  BH\/H 

As  an  illustration,  if  the  width  of  the  notch  is  4  ft.  and  the 
depth  of  water  on  the  weir  is  12  in.  the  quantity  of  water  avail- 
able per  second  is 

12    /12 
Q  =  3.33  X  4  X  y2\12  =  13'32  CU'  ft* 

Since  1  cu.  ft.  of  water  =  7.48  gal.,  the  quantity  of  water  de- 
livered in  gallons  is 

13.32  X  7.48  =  99.6  gal. 

Types  of  Water  Motors. — The  water  motors  mostly  used  at 
the  present  time  are  waterwheels,  which  are  made  to  revolve 
either  by  the  weight  of  water  falling  from  a  higher  to  a  lower  level, 
or  by  the  dynamic  pressure  which  is  produced  by  changes  in  the 
direction  and  velocity  of  flowing  water. 

Reciprocating  water  motors  are  used  to  a  limited  extent  for 
special  purposes.  Any  steam  engine  with  slight  modifications 
can  be  used  as  a  reciprocating  water  motor,  but  would  run  at 
slow  speed  on  account  of  the  incompressibility  of  water. 

Overshot,  Undershot  and  Breast  Wheels. — The  earlier  water 
motors  derived  their  power  from  the  weight  of  water  acting  on 
vanes  placed  around  the  rim  of  a  wheel. 

Of  these  the  overshot  wheel  receives  its  power  from  the  weight 
of  water  carried  by  buckets  on  the  circumference  of  a  wheel,  the 


214 


FARM  MOTORS 


water  entering  the  buckets  near  the  top  of  the  wheel  and  being 
discharged  near  the  bottom  (Fig.  207).  A  wheel  of  this  type  can 
be  constructed  easily  by  inserting  between  two  wooden  discs  a 
number  of  buckets,  made  like  V-shaped  troughs  (Fig.  207),  and 
putting  a  wooden  or  metal  shaft  at  the  center  of  the  discs. 
Water  is  supplied  from  an  open  trough  near  the  top  of  the  wheel. 
Motors  of  this  character  can  be  built  to  operate  on  falls  as  low 
as  4  ft.  and  will  supply  from  3  to  50  hp.,  depending  on  the  head 
of  the  fall  and  on  the  quantity  of  water  available. 


FIG.  207.— Overshot 
water  wheel. 


FIG.  208.— Undershot 
water  wheel. 


FIG.  209. — Breast 
water  wheel. 


The  undershot  wheel  is  propelled  by  water  passing  beneath 
it  in  a  direction  nearly  horizontal,  which  impinges  on  vanes 
carried  by  the  wheel.  Such  wheels  have  been  used  to  some  ex- 
tent for  irrigation  work.  Some  of  the  undershot  wheels  have 
straight  flat  projections  for  vanes  (Fig.  208),  but  the  more  effi- 
cient wheels  are  built  with  curved  vanes.  Such  motors  are  suit- 
able for  very  low  falls,  provided  the  velocity  of  the  water  is  great. 

The  breast  wheel  (Fig.  209)  receives  water  at  or  near  the  level 
of  its  axis,  but  is  otherwise  quite  similar  in  its  action  to  the  over- 
shot wheel.  Breast  wheels  are  provided  with  either  radial 
vanes,  or  with  vanes  slightly  curved  backward  near  the 
circumference. 

All  these  wheels  are  very  bulky  for  the  power  developed,  as 
compared  with  the  more  modern  types  of  impulse  water  motors. 

Impulse  Water  Motors. — Impulse  water  motors  are  provided 
with  buckets  or  cups  around  the  circumference  of  a  wheel,  which 
are  acted  upon  by  a  jet  of  water  issuing  from  a  nozzle. 

Among  impulse  water  motors,  the  Pelton  wheel  illustrated 
in  Fig.  210  is  used  to  a  considerable  extent  in  the  United 
States.  It  consists  of  a  series  of  cups  or  buckets  B  placed  at 


WATER  MOTORS 


215 


equal  intervals  around  the  circumference  of    an    iron    wheel. 

The  characteristic  feature  of  the  Pelton  motor  is  the  shape  of 

.  the  buckets.     These  are  made  in  the  form  of  two  half  cylinders 

with  closed  ends,  joined  together  at  the  center  by  a  straight 


FIG.  210.— Pelton  water  wheel. 

thin  rib.  The  power  is  derived  from  the  pressure  of  a  head  of 
water  supplied  by  a  pipe  which  discharges  upon  the  buckets  of 
the  wheel.  The  water  from  the  nozzle  N  striking  the  rib,  divides 


FIG.  211. — Water  motor. 

into  two  streams,  one  going  into  each  half  cylinder  and  exerting 
a  pressure  on  the  curved  surfaces  of  the  buckets.  The  Pelton 
water  motor  usually  is  furnished  with  two  nozzle  tips  of  dif- 
ferent diameters.  By  changing  the  tip,  the  size  of  the  stream  on 


216 


FARM  MOTORS 


the  wheel  is  altered  and  a  great  variation  in  power  may  be 
obtained. 

Pelton  water  motors  can  be  secured  in  very  small  sizes  under 
1  hp.  and  up  to  several  hundred  horsepower.  The  efficiency 
of  this  type  of  motor  is  greatest  at  high  heads,  but  in  small  sizes 
it  will  be  found  as  efficient  as  most  water  motors,  even  for 
heads  as  low  as  15  ft. 

Another  type  of  water  motor  illustrated  in  Fig.  211  is  made  in 
sizes  less  than  J£  hp.  and  can  be  used  for  running  washing 


FIG.  212— Water  Turbine. 

machines,  sewing  machines,  grindstones,  fans,  small  feed  grinders, 
and  for  other  purposes  requiring  little  power. 

An  impulse  water  motor  can  be  operated  from  city  water  mains 
or  from  an  independent  stream. 

Water  Turbines. — A  water  turbine  is  a  water  motor  which 
is  made  up  of  a  number  of  stationary  and  movable  curved 
pipes.  It  consists  of  the  following  parts: 

1.  A  gate  by  means  of  which  the  supply  of  water  to  the  tur- 
bine is  regulated. 


WATER  MOTORS 


217 


2.  A  guiding  element  consisting  of  stationary  blades,  the  func- 
tion of  which  is  to  deliver  the  water  to  the  revolving  element  in 
the  proper  direction  and  with  the  proper  velocity. 

3.  A  revolving  element  or  rotor,  consisting  of  vanes  or  buckets 


FIG.  213. — Water-power  installation. 

which  are  arranged  in  any  one  of  several  different  ways  around  the 
axis  of  the  motor. 

Water  turbines  are  divided  into  radial  outward-flow,  radial 
inward-flow  and  mixed-flow  types. 

In  the  radial  outward-flow  turbine  the  water  is  received  at  the 


218  FARM  MOTORS 

center  and  is  delivered  at  the  periphery  of  the  revolving  buckets. 
In  the  radial  inward-flow  types  the  stationary  or  guiding  element 
is  located  on  the  outside  of  the  revolving  part,  and  the  water 
flows  from  the  rim  toward  the  center. 

The  advantages  of  turbines  over  impulse  wheels  lie  in  the  fact 
that  a  turbine  can  be  utilized  for  very  low  falls.  The  turbines 
illustrated  in  Figs.  212  and  213  can  be  used  on  falls  as  low  as  4  ft. 
and  will  develop  about  3  hp.  with  a  water  supply  of  about  500 
cu.  ft.  per  minute. 

The  general  appearance  of  a  water-power  installation  with 
vertical  turbines  is  shown  in  Fig.  213. 

The  Hydraulic  Ram. — The  hydraulic  ram  combines  in  one 
simple  machine  a  motor  and  a  pump.  It  is  probably  the  simplest 


FIG.  214. — Hydraulic  ram. 

and  most  economical  method  for  supplying  water  for  the  farm 
house,  the  feed  yard,  the  barn  and  the  dairy  where  conditions  are 
favorable.  It  can  also  be  used  to  advantage,  under  certain  con- 
ditions, for  irrigating  small  tracts  of  land. 

Hydraulic  rams  are  low  in  first  cost  and  inexpensive  to  operate. 
They  are  not  economical  in  water,  as  a  large  amount  of  water 
must  be  wasted  in  comparison  with  the  work  done. 

The  working  of  the  hydraulic  ram  depends  on  the  fact  that  the 
momentum  of  a  large  quantity  of  water  falling  through  a  small 
height  is  capable  of  lifting  a  small  quantity  of  water  to  a  consider- 
able elevation. 

A  section  of  a  hydraulic  ram  is  shown  in  Fig.  214.  It  consists 
of  a  working  valve  7,  a  check  valve  D,  an  air  chamber  C,  a  drive 
pipe  A  which  supplies  water  to  the  ram,  and  a  delivery  pipe  B 
which  carries  the  water  to  the  place  where  it  is  utilized. 


WATER  MOTORS 


219 


The  ram  is  located  at  a  place  where  a  fall  of  2  to  10  ft.  can  be 
obtained.  The  water  from  the  source  enters  the  drive  pipe  (A  in 
Fig.  214)  and  flows  through  the  working  valve  V.  The  velocity 
of  water  in  this  pipe  increases  and  when  a  certain  velocity  is 
reached,  the  pressure  of  the  water  on  the  under  side  of  valve  V 
is  sufficient  to  close  it  abruptly.  The  flow  of  the  water  through 
the  working  valve  being  interrupted,  the  pressure  increases  and 
causes  the  check  valve  D  under  the  air  chamber  C  to  open,  and 
a  part  of  the  water  is  forced  into  the  air  chamber  compressing  the 
air  in  that  chamber.  The  velocity  of  the  water  in  the  drive  pipe 


FIG.  215. — Hydraulic  ram. 

having  been  arrested,  a  recoil  or  ramming  takes  place,  the  pres- 
sure in  the  space  below  the  air-chamber  check  valve  D  is  reduced, 
thus  closing  the  check  valve  D  and  allowing  the  working  valve  to 
open.  The  operations  are  then  repeated.  The  delivery  pipe 
to  the  storage  tank  at  a  higher  elevation  is  attached  to  the  air 
chamber  below  the  water  level.  The  air  under  compression  in 
the  air  chamber  forces  the  water  in  a  steady  stream  through  the 
delivery  pipe  B  and  to  the  storage  tank.  Hydraulic  rams  are 
also  provided  with  a  sniffing  valve,  not  shown  in  the  figure,  the 
function  of  which  is  to  replace  any  air  in  the  air  chamber,  lost  by 
being  dissolved  in  the  water. 

A  hydraulic  ram  is  illustrated  in  Fig.  215.    A  is  the  drive  pipe,  B 
the  discharge  pipe,  C  the  air  chamber  and  V  the  working  valve. 


220  FARM  MOTORS 

Problems:  Chapter  VIII 

1.  What  determines  the  power  available  in  a  stream? 

2.  Calculate  the  horsepower  available  in  a  stream  24  ft.  wide  and  6  ft. 
deep,  if  the  head  of  the  water  is  14  ft.  and  the  velocity  of  the  water  is  20  ft. 
per  minute.     Assume  the  losses  in  the  water  motor  equal  to  25  per  cent. 

3.  Give  directions  for  constructing  a  standard  weir  suitable  for  measuring 
water. 

4.  Calculate  the  gallons  of  water  flowing  over  a  weir  of  the  following 
dimensions:  width  of  notch  3  ft.,  depth  of  water  on  the  weir  15  in. 

6.  Explain,  using  clear  sketches,  the  Pelton  waterwheel. 

6.  What  are  the  fundamental  parts  of  a  water  turbine? 

7.  Explain,  using  clear  sketches,   the  construction  and  action   of  the' 
hydraulic  ram. 

8.  Report  on  the  future  of  water  power  for  rural  communities. 


CHAPTER  IX 
WINDMILLS 

Types  of  Windmills. — The  windmill  is  a  motor  which  converts 
the  kinetic  energy  of  the  wind  into  useful  work. 

Some  of  the  earlier  windmills  were  constructed  with  sails 
which  consisted  of  wooden  frames,  the  broad  sides  of  which  were 
covered  with  cloth.  These  sails  were  turned  by  the  wind  in 
horizontal  or  vertical  planes.  One  of  these  mills,  the  Dutch 
type,  is  illustrated  in  Fig.  216.  As  the  direction  of  the  wind 
changed,  the  entire  wheel-house,  including  shafting  and  ma- 
chinery, was  rotated  on  a  pivot  so  as 
to  bring  the  wheel  to  face  up  to  the 
wind.  This  limited  the  size  of  the 
mill.  In  the  latter  types  of  the 
Dutch  mill,  only  the  upper  part  of 
the  wheel-house  was  rotated.  These 
mills  were  governed  by  varying  the 
extent  of  the  sail  surface  exposed  to 
the  wind,  while  the  wheel  was  at  rest. 
The  Dutch  types  of  wooden  mills 
are  powerful,  but  bulky  and  expen-  FlQ'  216--Dutch  windmill, 
sive.  They  are  but  little  used  in  this  country  at  the  present 
time. 

The  American  mill  is  made  up  of  a  great  number  of  narrow 
blades  or  fans.  This  means  a  mill  of  smaller  weight  and  less  bulk 
than  the  Dutch  mill  of  the  same  power. 

Windmills  may  be  classified  as  pumping  and  power  windmills. 
The  pumping  windmill  gives  a  reciprocating  motion  to  a  vertical 
rod  suitable  for  operating  a  pump,  while  the  power  windmill 
gives  rotary  motion  to  a  shaft  through  a  train  of  gears. 

The  wheel  and  rudder  of  American  windmills  are  constructed 
either  of  wood  or  of  steel.  The  best  steel  windmills  are  galvan- 
ized for  protection  from  rust. 

Windmills  are  designated  by  the  diameter  of  the  wind  wheel. 
Thus  the  so-called  15-ft.  mill  has  a  wheel  15  ft.  in  diameter. 

221 


222 


FARM  MOTORS 


American  windmills  are  built  either  as  direct-stroke  or  as  back- 
geared.  In  the  case  of  the  direct-stroke  windmill  the  main 
shaft  carries  a  crank  which  is  attached  to  the  pump  rod  by  a  con- 
necting rod,  commonly  called  the  pitman,  there  being  no  speed- 
reducing  gears.  In  this  type,  the  pump  makes  one  complete 
stroke  for  each  revolution  of  the  wind  wheel.  Geared  mills  are 
back-geared,  so  that  the  pump  makes  one  stroke  for  every 
three  or  five  revolutions  of  the  wind  wheel.  The  back-geared 
mill  will  develop  more  power  than  the  direct-connected  mill  for  a 
wind  wheel  of  the  same  diameter. 

Principal  Parts  of  a  Windmill. — The  principal  parts  of  a  wind- 
mill are: 


FIG.  217.— Wind  wheel. 


FIG.  218. — Hub  of  wind  wheel. 


1.  A  wind  wheel  which  receives  the  kinetic  energy  of  the  wind. 
This  wheel  is  carried  upon  the  main  shaft. 

2.  A  rudder  or  vane  which  steers  the  wheel  against  the  wind. 

3.  A  governor,  which  regulates  the  speed  of  the  wind  wheel. 

4.  Gearing. 

5.  A  brake  which  holds  the  wheel  stationary  when  out  of  the 
wind. 

6.  Main  casting  which  supports  governor,  gearing  and  brake. 
This  with  the  parts  which  it  supports  is  called  the  mill  head. 

7.  A  tower  which  is  a  support  for  the  mill.     The  tower  should 
be  tall  enough  to  raise  the  wheel  sufficiently  high  above  all  ob- 
structions, such    as    trees,  houses,    etc.,   that  it  will  receive  a 
steady  breeze. 


WINDMILLS 


223 


The  Wind  Wheel.— The  wind  wheel  (Fig.  217)  is  that  part  of 
the  mill  which  derives  the  energy  from  the  wind. 

The  hub  of  the  wheel  either  consists  of  two  separate  wheel  spi- 
ders (Fig.  218)  keyed  to  the  main  shaft,  or  it  is  constructed  as  a 
solid  casting  with  the  wheel  spiders  at  either  end. 

The  arms  or  spokes  of  the  wheel  (S  in  Fig.  217)  are  attached 
to  the  wheel  spiders  (P)  and  extend  outward  to  the  rim  R.  The 
spokes  are  usually  of  rectangular  or  circular  cross-section,  but 
some  manufacturers  use  steel  angles. 

The  rims  are  placed,  one  near  the  inner  ends  of  the  fans  Fy  and 
the  other  either  a  little  beyond  the  center  or  near  the  outer  ends  of 
the  fans.  The  rims  are  made  either  of  strap  steel  or  of  angle 
steel. 


FIG.  219. — Fans  of  windmill. 


FIG.  220.— Samson  wheel. 


The  fans  (Figs.  217  and  219)  are  so  curved  that  the  wind  on 
leaving  one  fan  will  not  strike  upon  the  back  of  the  next.  The 
spacing  of  the  fans  is  such  that  the  wind  passes  through  freely 
and  all  parts  of  the  wheel  must  be  so  designed  as  to  offer  the 
least  resistance  to  the  wind.  The  fans  are  fastened  to  the  rims 
by  brackets  and  the  various  sections  of  fans  and  rims  are  riveted 
together. 

Fig.  220  shows  a  Samson  wheel  with  strap  steel  spokes  and 
hollow  hub. 

The  general  construction  of  a  wooden  wind  wheel  is  similar 
to  that  of  the  steel  wheel,  except  that  the  spokes,  rims  and  fans 
are  of  wood.  The  rims  are  made  either  straight  from  spoke  to 


224  FARM  MOTORS 

spoke  or  are  bent  in  a  manner  similar  to  that  of  steel  mills.  A 
section  of  a  wooden  wind  wheel  is  illustrated  in  Fig.  221.  The 
wooden  wind  wheel  is  made  up  of  six  or  more  sections,  each  sec- 
tion consisting  of  15  or  more  slats. 

The  Rudder  or  Vane. — Most  windmills  are  provided  with 
some  form  of  rudder  or  vane  for  keeping  the  wheel  in  the  direc- 


FIG.  221. — Section  of  wooden  wind  wheel. 

tion  of  the  wind.  In  some  windmills  no  rudder  is  employed,  and 
the  pressure  of  the  wind  on  the  wind  wheel  is  relied  upon  to 
bring  the  wheel  in  the  right  direction.  Windmills  without 
rudders  are  provided  with  folding  wheel  fans  and  have  a  weighted 


FIG.  222.— Steel  rudder. 


FIG.  223.— Wood  rudder. 

ball  which  performs  the  function  of  a  rudder  and  opens  the 
wheel  when  the  wind  is  greater  than  the  load.  Then  some  of  the 
larger  windmills  without  rudders  are  provided  with  a  small  side 
wheel  which  is  set  perpendicular  to  the  wind  wheel,  and  turns 
the  wind  wheel  into  the  proper  direction  by  means  of  gearing. 

The  rudder  is  built  either  of  steel  (Fig.  222)  or  of  wood  (Fig. 
223). 


WINDMILLS  225 

It  is  often  desired  to  throw  the  wind  wheel  out  of  action.  This 
in  the  case  of  the  folding  wheel  is  accomplished  from  the  ground 
level  by  a  wire  or  rod  which  extends  up  through  the  tower 
and  connects  with  a  system  of  levers  which  tip  the  sections  of 
the  wheel.  The  solid  wheel  is  thrown  out  of  action  either  by 
pulling  it  around  parallel  with  the  vane,  so  that  its  edge  faces 
the  wind,  or  by  pulling  the  vanes  parallel  to  the  wind. 

The  Governor — The  function  of  a  governor  is  to  regulate  the 
speed  of  the  wind  wheel. 

In  some  windmills  the  governor  consists  of  a  coiled  spring, 
one  end  of  which  engages  with  the  rudder  and  the  other  with  the 
mill  head.  When  the  wind  pressure  becomes  too  great,  the 
wheel  will  swing  so  as  to  expose  less  surface  to  the  wind. 

To  assist  in  governing,  some  mills  are  provided  with  a  side  vane. 

In  the  case  of  folding-wheel  mills  the  angle  of  the  fans  is 
changed,  by  a  system  of  weights  and  levers,  according  to  the 
intensity  of  the  wind. 

Most  windmills  are  provided  with  a  "  pull-out  reel,"  which 
consists  of  a  ratchet  and  windlass  for  throwing  the  wind  wheel 
out  of  action.  When  the  ratchet  is  released  the  wind  wheel  is 
thrown  into  correct  position  by  the  rudder  and  governor.  Some 
windmills  use  a  lever  instead  of  a  ratchet  and  windlass  for  the 
same  purpose. 

Windmill  Gearing. — The  gearing  of  a  direct-stroke  windmill 
is  illustrated  in  Fig.  224. 

One  simple  form  of  a  back-geared  mill  mechanism  is  given  in 
Fig.  225.  E  represents  the  hub  of  the  wind  wheel.  The  pinion 
P  is  carried  on  the  main  shaft  and  meshes  with  a  large  gear  A  on  a 
countershaft.  The  center  of  the  gear  A  is  placed  to  one  side  of 
the  upper  end  of  the  connecting  rod  or  pitman  B,  so  that  it 
requires  more  than  half  of  a  revolution  to  raise  the  pump  rod  and 
less  than  half  of  a  revolution  to  lower  it.  Thus  a  quick  return 
motion  is  obtained,  the  pump  rod  descending  more  rapidly  than 
it  rises.  This  is  advantageous  in  that  little  power  is  required 
on  the  down-stroke,  there  being  no  water  raised  and  the  weight 
of  the  plunger,  pump  pole  and  pump  rod  being  sufficient  to 
produce  that  stroke.  The  slow  motion  on  the  up-stroke  enables 
the  mechanism  to  carry  the  load  with  the  least  strain.  In  this 
mechanism  D  is  a  hinge  for  attaching  the  rudder  or  vane. 

15 


226 


FARM  MOTORS 


The  difference  in  construction  between  the  gearing  for  pump- 
ing and  power  windmills  is  in  the  addition  of  a  bevel  gear  B 
(Fig.  226)  which  meshes  with  another  bevel  gear  on  the  power 
shaft. 

All  windmills  should  be  provided  with  some  form  of  buffer  to 
protect  the  rudder  and  other  parts  from  sudden  shocks  when  the 
windmill  is  thrown  out  of  gear.  The  buffer  is  usually  constructed 


FIG.  224. — Direct-stroke  windmill. 


FIG.  225. — Back-geared  windmill. 


in  the  form  of  a  helical  steel  spring  placed  upon  the  rudder  rail 
near  the  hinge. 

Windmill  Brake. — Nearly  all  windmills  are  provided  with  an 
automatic  brake,  which  holds  the  wheel  stationary  when  out  of 
the  wind.  The  brake  is  a  flexible  steel  band  which  encircles 
about  three-fourths  of  the  flange  on  the  hub  of  the  wind  wheel 
and  holds  it  stationary  when  out  of  gear.  The  brake  is  applied 
by  a  lever  as  soon  as  the  windmill  is  turned  out  of  gear. 

Towers. — Windmill  towers  are  constructed  either  of  wood  or 
of  steel. 

There  are  a  great  many  different  kinds  of  wooden  towers,  as 


WINDMILLS  227 

they  are  often  "home-made."  Four  4-in.  by  4-in.  or  6-in.  by 
6-in.  timbers,  depending  on  the  size  of  the  tower,  are  most  com- 
monly employed  for  the  corner  posts.  They  are  spread  about 
8  or  10  ft.  at  the  bottom  and  are  brought  together  at  the  top 
and  fastened  to  a  cast-iron  cap,  usually  provided  by  the  manu- 
facturer. A  platform  2  or  3  ft.  square  should  be  provided 
directly  below  the  wind  wheel  for  the  purpose  of  facilitating 
oiling,  inspection  and  repairing.  The  tower  ends  of  the  corner 


FIG.  226. — Power  windmill. 

posts  are  bolted  to  anchor  posts  which  are  set  about  6  ft.  in  the 
ground  with  cross-pieces  bolted  to  the  lower  end  to  form  a 
better  foundation. 

Steel  windmill  towers  are  built  with  either  three  or  four 
posts  and  should  always  be  galvanized  and  not  painted.  A  tower 
supported  on  four  posts  (Fig.  227)  is  protected  from  a  wind  in 
any  direction.  The  three-post  tower  (Fig.  228)  is  somewhat 
cheaper  than  the  four-post  tower,  and  has  the  additional  advan- 


228 


FARM  MOTORS 


FIG.  227.— Four-post  tower. 


WINDMILLS 


229 


FIG.  228.— Three-post  tower. 


230 


FARM  MOTORS 


tages,  in  localities  where  the  ground  is  soft,  of  always  standing 
firm  and  rigid,  and  of  being  unaffected  by  unequal  settling  of 
anchor  posts.  A  three-post  tower  when  properly  braced  also  is 
stiffer  and  stronger  than  a  four-post  tower. 

The  corner  posts  of  a  steel  tower  are  usually  of  angle  steel, 
but  some  are  of  gas  pipe.  The  cross-girts  are  of  angle  steel  and 
the  braces  may  be  of  angle  steel,  rods,  or  wire  cable.  The  anchor 
posts  are  about  6  ft.  long  and  of  the  same  material  as  the  corner 
posts,  with  anchor  plates  attached  at  the  lower  end. 

The  method  of  fastening  the  corner  posts  of  three-  and  four- 
post  towers  is  shown  in  Fig.  229.  The  posts  are  beveled,  notched 
and  are  held  together  by  clamps  and  bolts. 


FIG.  229. — Method  of  fastening  corner  posts  of  three-post  and 
four-post  towers. 

The  tower  in  Fig.  230  has  the  lower  braces  of  angle  steel  and 
the  other  braces  of  rods.  Twisted- wire  cable  braces  are  shown 
in  Fig.  231. 

Method  of  Erecting  Windmills. — A  windmill  is  erected  either 
by  building  it  up  in  position  piece  by  piece,  or  it  is  assembled 
on  the  ground  and  then  raised  into  position.  The  method  of 
raising  a  windmill  from  the  ground  is  illustrated  in  Fig.  232. 

After  the  holes  for  the  anchor  posts  are  dug,  the  anchor  posts 
are  placed  loosely  in  them.  In  raising  towers  over  30  ft.  in 
height,  the  lower  portion  should  be  reinforced  by  placing  timbers 
in  the  tower  (Fig.  232).  A  beam  of  wood  is  then  placed  across 
the  lower  ends  of  the  legs,  and  stakes  are  driven  at  each  end,  in 
order  to  prevent  the  tower  from  sliding  when  it  is  being  raised. 
A  strong  rope  is  attached  to  the  tower  near  the  platform  and  to 


WINDMILLS 


231 


FIG.  230. — Tower  of  aermotor  windmill. 


\ 


FIG.  231.— Twisted  wire  braces. 


232 


FARM  MOTORS 


Fia.  232. — Method  of  raising  windmill  from  the  ground. 


WINDMILLS  233 

a  block  and  tackle  a  little  beyond  the  lower  end  of  the  tower. 
Another  block  is  made  fast  to  some  stakes  driven  at  a  distance 
of  one  and  one-half  times  the  length  of  the  tower  from  the  lower 
end  of  the  tower.  Shear  poles  about  one-half  the  length  of 
the  tower  are  then  placed  under  the  rope  near  the  lower  end 
of  the  tower.  Stakes  are  driven  at  each  side  of  the  upper 
end  of  the  tower,  to  which  ropes  are  attached  to  retain  the  tower 
in  position,  and  the  tower  is  pulled  into  position  by  a  traction 
engine,  team,  or  windlass.  Several  men  usually  can  raise  a  small 
tower  by  pulling  directly  on  the  tackle  rope. 

When  the  tower  is  nearly  erect,  the  two  front  anchor  posts 
should  be  bolted  on  and  the  rear  guy  line  payed  off  until  the  two 
anchor  posts  come  into  place  on  the  bottom  of  the  holes.  The' 
tower  is  then  tilted  back  and  the  other  two  anchors  are  attached 
in  the  same  way. 

After  the  tower  is  in  position  it  should  be  leveled  with  a 
plumb  bob,  before  the  pump  rod  is  put  into  place.  All  braces 
must  be  evenly  tightened. 

Loose  stones  are  often  placed  below  and  above  the  anchor 
plate.  For  best  results  a  concrete  base  should  be  used.  When 
using  loose  stones,  it  is  desirable  that  the  anchor  plates  should 
rest  on  cap  stones. 

Care  of  Windmills. — A  windmill  requires  some  care  if  long 
and  good  service  is  expected. 

When  first  erected  it  should  be  carefully  examined  every  few 
days  for  loose  bolts  and  bearings. 

All  bearings  should  be  kept  well-lubricated  and  brasses  tight. 
If  anchor  posts  work  loose,  they  should  be  reset.  It  is  always 
well  to  shut  down  a  windmill  during  a  heavy  storm. 

Windmills  may  be  lubricated  by  means  of  oil  cups,  the  oil 
being  held  in  place  by  waste.  With  the  ordinary  oil  cups  a 
windmill  would  have  to  be  lubricated  every  2  or  3  days  if  it  were 
running  continuously.  To  reduce  the  necessity  of  frequent 
lubrication,  some  form  of  self-feed  oil  cup  is  used.  This  consists 
of  a  large  oil  cup  with  a  tube  extending  nearly  to  the  top  of 
the  oil  cup.  A  twisted-wire  wick  passes  from  the  bottom  of 
the  oil  cup  into  the  tube.  The  oil  from  the  cup  follows  the  wick- 
ing  into  the  tube  and  lubricates  the  bearing  which  is  at  the 
bottom  of  the  tube. 


234 


FARM  MOTORS 


Power  of  Windmills. — The  power  delivered  by  a  windmill 
depends  on  the  velocity  of  the  wind,,  on  the  size  and  construction 
of  the  wheel,  on  the  amount  of  power  lost  in  friction  and  on  the 
density  of  the  air. 

It  has  been  found  that  an  average  wind  velocity  of  6  miles  per 
hour  is  required  to  drive  a  windmill.  The  average  velocity  of 
the  wind  in  the  United  States  varies  from  4.2  to  16  miles  per 
hour.  The  best  wind  velocity  is  about  15  miles  per  hour. 
The  velocity  in  most  localities  is  great  enough  to  operate  a  mill 
about  8  hr.  per  day. 

The  power  developed  by  a  windmill  with  winds  of  average 
intensity  will  vary  from  J£  hp.  for  a  6-ft.  wind  wheel  to  about 
'1  hp.  for  a  16-ft.  wind  wheel.  With  strong  winds  and  with 
large  wheels,  windmills  will  develop  as  much  as  4  hp. 

TABLE  7. — POWER  OF  WINDMILLS 


Wind  velocity,  miles  per  hour 

Indicated  horsepower 

12-ft.  wheel 

16-ft.  wheel 

8 

0.10 

0.18 

10 

0.20 

0.36 

12 

0.34 

0.60 

15 

0.67 

1.21 

20 

1.60 

2.90 

25 

3.12 

5.50 

30 

5.40 

8.50 

The  angle  and  spacing  of  the  wind-wheel  fans  affect  the  power 
delivered  by  a  windmill.  Then  the  quality  and  condition  of  the 
gearing  and  bearings  determine  the  actual  power  available  for 
utilization  either  at  the  pump  or  power  shaft. 

The  density  of  the  air  affects  the  pressure  of  the  wind  on  the 
wind  wheel.  Thus  the  higher  the  altitude  the  lighter  is  the  air 
and  the  less  power  is  developed  with  a  wind  of  a  certain  velocity. 

The  cost  of  windmill  power  is  about  5  cents  per  horse  power 
per  hour,  when  considering  cost  of  attendance,  repairs,  cost  of 
lubrication  and  interest  on  investment. 

Uses  of  Windmills. — The  main  use  of  windmills  is  for  pumping 
water  for  domestic  use  and  for  stock.  When  used  in  pumping 


WINDMILLS  235 

water  for  irrigation,  a  storage  tank  of  large  capacity  should  be 
provided,  sufficient  for  several  days'  use  in  case  of  calm  weather. 

For  watering  stock  on  small  farms  and  for  domestic  use  on  the 
farm,  the  windmill  is  the  cheapest  and  best  form  of  motor.  It 
requires  but  little  attention.  One-half  hour  per  week  devoted  to 
oiling  and  inspection  will  keep  the  mill  in  good  condition. 

A  windmill  cannot  be  used  for  heavy  work  on  the  farm,  but 
can  drive  small  feed  grinders,  grindstones,  corn  shellers,  feed 
cutters,  wood  saws,  churns,  or  any  other  machine  requiring  little 
power. 

In  general  the  windmill  is  suitable  for  work  requiring  but  little 
power,  which  will  admit  of  suspension  during  calm  weather. 

Problems:  Chapter  IX      .  .. 

1.  Explain  the  Dutch  type  of  windmill.     Why  is  this  type  of  mill  not 
used  in  the  United  States? 

2.  What  are  the  principal  parts  of  a  windmill? 

3.  How  are  windmills  rated? 

4.  Explain  the  construction  of  the  wind  wheel. 
6.  What  is  the  function  of  the  vane  or  rudder? 

6.  Explain  construction  and  action  of  some  type  of  windmill  governor. 

7.  Explain  in  detail  the  action  of  the  direct-stroke  windmill  illustrated  in 
Fig.  224. 

8.  Show  by  means  of  sketches  or  illustrations  the  difference  between  the 
power  windmill  and  the  windmill  which  is  designed  for  pumping  only. 

9.  Give  directions  for  building  a  modern  windmill  tower. 

10.  Compare  the  advantages  and  the  disadvantages  of  the  three-post  and 
the  four-post  windmill  tower. 

11.  Give  directions  for  erecting  a  windmill. 

12.  Report  on  the  uses  of  the  windmill  for  irrigation  and  for  the  genera- 
tion of  electricity. 


CHAPTER  X 
.  GENERATORS,  ELECTRIC  MOTORS  AND  BATTERIES 

Before  considering  the  various  types  of  electric  motors  and  their 
applications,  the  fundamentals  of  electricity  and  of  dynamo 
electric  machinery  will  be  taken  up. 

Action  of  Electricity. — The  action  of  electricity  in  an  electric 
generator  is  analogous  to  that  of  water  pumped  from  a  lower  to 
a  higher  level.  The  function  of  a  pump  in  forcing  water  through 
pipes  is  well  known.  The  pump  exerts  a  pressure  on  the  water. 
If  the  pressure  exerted  by  the  pump  is  doubled,  the  quantity  of 
water  handled  by  the  pump  will  also  be  doubled,  if  the  friction  of 
the  water  through  the  pipe  remains  the  same.  It  is  also  well 
known  that  the  resistance  offered  to  the  flow  of  water  through 
pipes  increases  with  the  length  of  the  pipe.  Also  by  increasing 
the  size  of  the  pipe  the  resistance  is  decreased. 

The  generator  in  the  electric  power  plant  performs  a  function 
similar  to  that  of  the  pump.  It  generates  electrical  pressure  in 
order  to  send  electricity  through  the  wires  which  correspond  to 
pipes.  The  resistance  offered  by  the  wire  to  the  flow  of  electricity 
is  analogous  to  that  offered  by  the  water  pipe  to  the  flow  of  water. 
The  quantity  of  electricity  delivered  to  the  circuit,  which  may 
consist  of  motors,  lamps,  or  other  appliances  using  electricity, 
corresponds  to  the  amount  of  water  delivered  by  the  pump  to  an 
overhead  tank  or  pipe  from  which  water  motors  or  other  appli- 
ances requiring  water  under  pressure  can  be  operated. 

Units  of  Electricity. — The  pound  is  the  unit  of  water  pressure, 
while  the  unit  of  electricity  is  the  volt.  The  amount  of  water 
flowing  through  a  pipe  is  measured  in  gallons  per  minute,  the 
quantity  of  electricity  flowing  through  a  wire  in  amperes.  The 
resistance  which  a  wire  offers  to  the  flow  of  electricity  is  measured 
in  ohms. 

The  unit  of  electrical  power  is  the  watt,  a  watt  being  the  prod- 
uct of  a  volt  and  ampere.  The  power  available  in  a  certain 
weight  of  water  depends  on  the  head,  or  on  the  distance  the 

236 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        237 

water  is  allowed  to  fall.  Similarly  the  power  available  at  the 
terminals  of  a  generator  is  the  product  of  the  quantity  of  elec- 
tricity in  amperes  and  the  electrical  pressure  head  in  volts. 

As  an  illustration,  the  power  available  at  the  terminals  of  a 
generator  delivering  60  amp.  at  110  volts  is 

Power  in  watts  =  60  X  110  =  6,600 

Generators  usually  are  rated  in  kilowatts  (kw.),  a  kilowatt 
being  1,000  watts.  Electric  motors  are  rated  in  electrical  horse- 
power, an  electrical  horsepower  being  equal  to  746  watts.  The 
relation  between  the  kilowatt  and  the  electrical  horsepower  is 
1,000 


Thus  an  electric  motor  operating  on  a  220-volt  circuit  and 
requiring  30  amp.  has  delivered  to  it 

220  X  30 
—  =v~  —  =  8.85  electrical  horsepower. 

If  the  efficiency  of  the  motor  is  80  per  cent.,  the  available  power 
at  the  motor  shaft  is  8.85  X  0.80  =  7.08  b.  hp. 

Ohm's  Law.  —  The  law  expressing  the  relation  between  the 
volt,  the  ampere  and  the  ohm  is  of  great  value  in  electrical 
calculations.  It  is  called  Ohm's  law  and  is  expressed  by  the 
statement  that 

Pressure  in  volts 

I  he  current  in  amperes  =  -F;  —  =—  r  -  =  -  \  - 

Resistance  in  ohms. 

Expressing  the  current  by  the  symbol  7,  the  voltage  by  E  and 
the  resistance  by  R 

I  =  * 
R 

As  an  illustration,  an  ordinary  16-cp.  carbon  lamp  operating 
on  a  110-  volt  circuit  offers  a  resistance  of  220  ohms.  How  much 
current  will  be  required  to  operate  the  lamp? 

Applying  Ohm's  law  — 

E       110  volts       1 


The  power  required  to  operate  the  lamp  is 

1 

110  X  o  =  55  watts. 


238 


FARM  MOTORS 


Considering  no  losses  in  the  engine,  generator  and  lines,  the  num- 
ber of  16-cp.  carbon  lamps  which  can  be  operated  by  a  generator 
driven  from  a  1-hp.  engine  is 


=  13.56  lamps. 
oo 

Due  to  line  losses  and  to  losses  in  the  generator,  it  is  customary 
to  figure  about  ten  16-cp.  carbon-filament  lamps  per  engine 
horsepower. 

Incandescent  Lamps.  —  Table  8  shows  the  current  consumed 
by  carbon-filament  and  by  tungsten-filament  lamps  of  various 
candlepowers.  From  this  table  it  is  evident  that  the  tungsten- 
filament  lamp  consumes  about  one-third  the  current  required 
by  carbon-filament  lamps  of  the  same  candlepower.  A  tungsten- 
filament  lamp  will  require  about  1.25  watts  per  candlepower 
and  will  give  a  whiter  light  than  the  carbon-filament  lamp. 

TABLE  8.  —  CURRENT  CONSUMED  BY  INCANDESCENT  LAMPS  AT  110  VOLTS 


Amperes 

Watts 

Candlepower 

Carbon 

Tungsten 

Carbon 

Tungsten 

8 

0.25 

28 

16 

0.50 

55 

20 

0.228 

25 

32 

1.00 

0.364 

110 

40 

48 

— 

0.545 

... 

60 

Wires  for  Conductors  of  Electricity. — The  resistance  which 
a  wire  offers  to  the  flow  of  electricity  depends  on  its  cross-section 
and  on  the  material  from  which  it  is  made.  Silver  when  pure 
is  considered  to  be  the  best  conductor.  Copper  is  very  nearly 
as  good  a  conductor  as  silver,  and,  being  much  cheaper,  it  is 
used  in  nearly  all  cases  for  the  distribution  of  electricity. 

Copper  wire  is  sometimes  used  bare,  but  in  most  cases  it  is 
covered  with  a  material  called  insulation,  to  prevent  the  transfer 
of  electricity  to  surrounding  substances.  The  insulation  used 
on  wire  is  either  rubber  or  some  weather-proof  substance. 

Copper  wires  are  designated  either  by  the  Brown  and  Sharpe 
wire  gage  (B.  &  S.  gage)  or  by  their  cross-section  in  circular 
mils.  A  circular  mil  is  a  circle  J-fooo  in.  in  diameter.  The 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        239 


designation  of  wire  by  the  B.  &  S.  gage  is  more  common  for  small 
wires.  This  gage  is  constructed  so  that  the  numbers  decrease 
as  the  size  of  the  wire  increases.  Thus  a  No.  10  B.  &  S.  wire  is 
smaller  than  a  No.  9  and  larger  than  a  No.  11. 

The  current-carrying  capacities  in  amperes  of  various  sizes 
of  rubber-covered  and  weather-proof  wire  are  given  in  Table  9. 

TABLE  9. 


Size  of  copper  wire 

Current-carrying  capacity  in  amperes 

B.  &  S.  gage 

Circ.  mils 

Rubber-covered  wire 

Weather-proof  wire 

18 

1,624 

3 

5 

16 

2,583 

6 

8 

14 

4,107 

12 

16 

12 

6,530 

17 

23 

10 

10,380 

24 

32 

8 

16,510 

33 

46 

6 

26,250 

46 

65 

5 

33,100 

54 

77 

4 

41,740 

65 

92 

3 

52,630 

76 

110 

2 

66,370 

90 

131 

1 

83,690 

107 

156 

0 

105,500 

127 

185 

00 

133,100 

150 

220 

000 

167,800 

177 

262 

0000 

211,600 

210 

312 

The  sizes  of  wire  in  the  tables  are  given  in  terms  of  the  B.  &  S. 
gage  as  well  as  in  circular  mils. 

Electrical  Batteries. — Batteries  are  used  mainly  in  places 
where  the  current  requirement  is  small,  as  in  connection  with 
the  ignition  systems  of  internal-combustion  engines,  also  for 
operating  telephones,  telegraphs,  electric  bells,  etc. 

Batteries  can  be  called  chemical  generators  of  electricity,  and 
are  of  two  types.  One  type,  called  the  primary  battery,  generates 
electrical  current  by  means  of  direct  chemical  action  between 
certain  substances.  Another  type,  called  a  secondary  battery 
or  storage  battery,  requires  charging  with  electricity  from  some 
outside  electric  source  before  it  will  generate  electrical  energy. 
The  outside  current  acting  on  the  substances  within  the  battery 


240  FARM  MOTORS 

changes  their  chemical  properties  to  such  an  extent  that  the 
battery  is  able  to  deliver  current  when  connected  to  a  circuit. 
After  storage  batteries  furnish  current  to  a  circuit  for  a  certain 
length  of  time,  their  active  materials  become  nearly  exhausted 
and  they  must  be  recharged  with  electricity  before  they  can  be 
used  again.  Here  lies  the  difference  between  the  storage 
battery  and  the  ordinary  primary  battery.  The  active  materials 
in  the  primary  battery  when  once  exhausted  cannot  be  brought 
back  to  generate  electricity,  and  must  be  renewed. 

The  term  battery  is  applied  to  two  or  more  cells,  whether 
primary  or  storage  types,  which  are  connected  together  to  in- 
crease the  total  amount  of  electrical  energy  delivered  to  a 
circuit. 

Primary  Batteries. — A  primary  cell  consists  essentially  of  a 
vessel  containing  some  acid  called  the  electrolyte  in  which  are 
immersed  two  solid  conductors  of  electricity,  called  electrodes, 
one  of  which  is  more  easily  attacked  by  the  acid  than  the  other. 
A  simple  cell  consists  of  a  weak  solution  of  sulphuric  acid,  as 
an  electrolyte,  a  plate  of  zinc,  which  is  easily  decomposed  by  the 
sulphuric  acid,  and  a  plate  of  some  other  solid  like  copper  or 
carbon  which  resists  the  action  of  sulphuric  acid.  If  the  plates 
of  zinc  and  copper  are  put  side  by  side  in  a  vessel  containing 
sulphuric  acid,  and  the  circuit  is  completed  by  joining  the  two 
plates  by  a  wire,  chemical  action  will  be  set  up  within  the  vessel 
or  cell.  The  zinc  will  dissolve  in  the  acid,  forming  zinc  sulphate, 
hydrogen  will  be  given  up  by  the  sulphuric  acid  in  streams  of 
bubbles  which  will  settle  on  the  copper  plate,  and  a  current  of 
electricity  will  be  generated.  The  bubbles  of  hydrogen  liberated 
from  the  electrolyte  do  not  combine  with  the  copper  plate,  but 
form  a  gaseous  non-conducting  film  over  the  metallic  surface 
which  increases  the  resistance  of  the  cell  to  the  flow  of  electric 
current.  The  formation  of  the  bubbles  of  hydrogen  on  the  copper 
plate,  called  polarization,  causes  a  rapid  falling  off  in  the  power. 
It  is  possible  to  decrease  or  even  eliminate  polarization.  One 
good  method  is  to  construct  the  cell  with  some  strong  oxidizing 
agent.  The  oxidizing  agent  gives  up  its  oxygen,  which  combines 
with  the  particles  of  hydrogen,  forming  water  and  decreasing 
polarization.  Cells  using  this  method  of  decreasing  polarization 
usually  employ  carbon  plates,  as  most  of  the  oxidizing  materials 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        241 


attack  copper  plates.     The  Leclanche  cell  shown  in  Fig.  233  is 
an  example  of  this  type  of  cell. 

The  dry  cell,  which  is  used  extensively  at  the  present  time  on 


FIG.  233.— Leclanche  cell. 


FIG.  234. — Dry  cells. 


account  of  its  portability,  is  a  modification  of  the  Leclanche  cell. 

It  has  zinc  for  the  positive  electrode,  carbon  for  the  negative 

electrode,  sal  ammoniac  and  zinc  chloride  as  the  electrolyte  for 

decomposing  the  zinc,   and    some    oxidizing 

agent  like  manganese  dioxide    to   eliminate 

polarization.      As   usually    constructed,    the 

dry  cell  consists  of  a  zinc  cylinder  which  is 

the  positive  electrode  and  acts  at  the  same 

time  as  a  container  for  the  other  materials 

of  the    cell.     The  zinc   cylinder  is  provided 

with  a  lining  composed  of  plaster  of  paris, 

flour,  blotting-paper,  or  some  other  absorbent 

material  saturated   with  sal   ammoniac  and 

zinc  chloride.     At  the  center  of  the  cell  is  a 

carbon    rod,   and    this   is   surrounded   by   a 

paste  consisting  of   manganese   dioxide    and 

chloride  of  zinc.      The   top    of   the   cell    is 

covered  with  a  layer  of  hard  pitch.     A  small 

hole  through  the  pitch  permits  the  escape  of 

gases  which  may  be  formed  within  the   cell.     The  outside  of 

the  cell    usually   is   insulated    with    paper.      Several  forms  'of 

dry  cells  are  illustrated  in  Fig.  234.     The  solution  in  the  dry 

it 


FIG.  235. —  Edison 
Lalande  cell. 


242  FARM  MOTORS 

cell  evaporates  slowly,  so  that  a  battery  of  dry  cells  will  be- 
come worthless  after  a  certain  time  even  if  it  is  not  used. 
Generally  a  dry  cell  in  good  condition  will  have  a  current 
strength  of  15  to  25  amp.  and  should  show  a  pressure  of  \Y±  to 
1%  volts.  A  binding  post  is  attached  to  the  carbon  and 
another  one  to  the  edge  of  the  zinc  cylinder. 

The  various  Lalande  wet  cells  are  very  good  for  gas-engine 
ignition.  One  form,  the  Edison  Lalande,  is  illustrated  in  Fig. 
235.  One  electrode  in  this  cell  is  of  zinc  and  the  other  of  copper 
oxide.  The  electrolyte  consists  of  caustic  potash.  The  oxygen 
of  the  copper  oxide  prevents  polarization.  A  film  of  heavy 
paraffin  oil  is  put  on  top  of  the  electrolyte,  so  as  to  prevent  the 
absorption  of  carbon  dioxide  from  the  air  by  the  caustic  potash. 

Storage  Batteries. — A  storage  battery  consists  of  two  sets  of 
plates  or  electrodes  known  respectively  as  positive  and  negative, 
submerged  in  a  liquid  called  the  electrolyte  The  plates  are 
encased  in  a  jar  or  container.  This  type  of  battery  must  be 
charged  frequently  with  electricity  in  order  to  give  out  current  to 
the  external  circuit.  The  storage  battery  does  not  store  elec- 
tricity, but  energy  in  the  form  of  chemical  work.  The  electric 
current  produces  chemical  changes  in  the  battery  and  these 
changes  produce  a  current  in  the  opposite  direction  when  the 
circuit  is  closed. 

Storage  batteries  are  used  for  gas-engine  ignition  and  are  pre- 
ferred for  this  purpose  to  primary  dry  or  wet  batteries  on  account 
of  their  greater  capacity  and  more  uniform  voltage.  Modern 
automobiles,  as  explained  in  Chapter  VI,  employ  storage  batter- 
ies for  starting,  lighting  and  ignition.  Storage  batteries  are  also 
used  to  a  considerable  extent  for  farm  lighting  in  order  to  shorten 
the  time  required  for  operating  the  engine  and  electric  generator. 

The  capacity  of  a  storage  battery  is  measured  in  ampere-hours 
determined  by  multiplying  the  current  rate  of  discharge  by  the 
number  of  hours  of  discharge  of  which  the  battery  is  capable  at 
that  rate.  As  an  illustration,  a  battery  that  will  deliver  10  amp. 
for  8  hr.  has  a  capacity  of  80  amp.-hr.  The  ampere-hour  capac- 
ity of  a  storage  battery  is  dependent  upon  the  rate  of  discharge. 
Most  manufacturers  specify  the  rate  of  discharge  for  their  par- 
ticular make  of  storage  batteries.  If  the  rate  of  discharge  is 
greater  than  the  specified  amount,  the  capacity  of  the  battery  is 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        243 

reduced.  If  a  storage  battery  has  a  capacity  of  80  amp.-hr.  at 
the  10-amp.  rate,  it  will  have  a  greater  ampere-hour  capacity  if 
discharged  at  a  5-amp.  rate;  that  is,  it  will  deliver  a  current  of  5 
amp.  for  more  than  16  hr.  The  normal  rate  of  discharge  is  the  8- 
hr.  period. 

A  storage  battery  can  be  charged  from  any  direct-current  cir- 
cuit, provided  the  voltage  of  the  charging  circuit  is  greater  than 
that  of  the  storage  battery  when  fully  charged.  Before  a  stor- 
age battery  is  connected  to  the  charging  circuit  its  polarity  should 
be  carefully  determined,  and  the  positive  and  negative  terminals 
of  the  battery  connected  to  the  positive  and  negative  terminals  of 
the  source  respectively.  One  good  method  of  determining  the 
polarity  of  the  wires  from  the  storage  battery  or  source  is  to 
immerse  them  in  a  glass  of  salt  water.  Bubbles  of  gas  will  form 
more  rapidly  on  the  surface  of  the  negative  wire.  Another  test 
is  that  the  negative  wire  will  turn  blue  litmus  paper  red.  Should 
the  positive  wire  of  the  battery  be  connected  to  the  negative  wire 
of  the  source,  the  effect  would  be  a  discharge  of  the  battery,  and 
this  being  assisted  by  the  incoming  current,  a  reversal  of  action 
would  take  place,  which  is  very  injurious  to  the  battery.  It  is 
not  well  to  charge  a  battery  at  too  rapid  a  rate,  as  this  will  raise 
its  temperature  and  will  cause  buckling  of  the  battery  plates.  It 
is  well  also  to  charge  batteries  at  regular  intervals. 

Two  types  of  storage  batteries  are  used,  the  lead  storage 
battery  and  the  Edison.  The  Edison  battery  is  also  called  the 
alkaline  or  the  nickel-iron  battery. 

The  Lead  Storage  Battery. — In  the  lead  storage  battery  both 
the  positive  and  the  negative  electrodes  of  a  cell  are  of  perforated 
lead  plates.  The  perforations  are  filled  with  certain  lead  com- 
pounds (PbsO4  and  PbO)  which  react  with  the  electrolyte  of  di- 
lute sulphuric  acid,  forming  lead  peroxide  on  the  positive  plate  and 
a  spongy  metallic  lead  on  the  negative  plate.  The  lead  peroxide 
and  the  spongy  metallic  lead  are  both  converted  into  insoluble 
lead  sulphate  (PbSO4)  when  this  cell  delivers  current,  and  this 
lead  sulphate  is  converted  back  into  lead  peroxide  and  spongy 
lead  respectively  when  a  reversed  current  is  forced  through  the 
cell.  The  lead  peroxide  and  spongy  lead  are  called  the  active 
materials  of  the  cell. 

The  voltage  of  the  cell  increases  with  the  increased  concentra- 
tion of  its  electrolyte,  which  is  sulphuric  acid.  When  the  cell  is 


244  FARM  MOTORS 

completely  charged,  the  electrolyte  is  more  concentrated  and  the 
voltage  is  large.  As  the  cell  is  discharged,  the  concentration  of 
the  sulphuric  acid  is  decreased  and  the  voltage  drops. 

A  lead  cell  when  fully  charged  will  show  2.2  to  2.5  volts  on 
open  circuit  and  about  2.15  volts  when  the  circuit  is  closed.  A 
lead  storage  battery  should  not  be  allowed  to  discharge  to  a  vol- 
tage lower  than  1.8  volts  while  giving  its  full  rated  current. 

The  storage  cell  is  composed  of  an  odd  number  of  positive 
plates  and  of  an  even  number  of  negative  plates,  so  that  each 
side  of  a  positive  plate  faces  a  negative  plate.  The  plates  are 
insulated  from  each  other  and  from  the  bottom  and  are  placed  in 
a  glass  vessel,  if  the  battery  is  to  be  used  for  stationary  purposes, 
and  in  a  vessel  of  hard  rubber  if  the  battery  is  for  portable  use. 
Various  forms  of  lead  storage  batteries  are  illustrated  in  Fig.  236. 


FIG.  236. — Lead  storage  batteries. 

The  positive  and  the  negative  plates  of  a  storage  battery  can  be 
distinguished  by  their  color.  The  positive  plates,  when  fully 
charged,  should  have  a  dark  brown  or  chocolate  color,  and  the 
negative  plates  more  of  a  light  gray  or  a  metallic  lead  color. 

Lead  storage  batteries  deteriorate  rapidly  in  service,  if  not 
properly  cared  for. 

For  successful  operation  and  long  life,  storage  batteries  should 
be  tested  frequently  with  a  pocket  voltmeter  for  voltage  and 
with  a  hydrometer  for  the  specific  gravity  of  the  electrolyte.  A 
battery  hydrometer  for  measuring  the  specific  gravity  is  illus- 
trated in  Fig.  237.  The  specific  gravity  of  the  electrolyte  of  a 
stationary  battery  should  be  1.17  to  1.22  when  the  battery  is 
fully  charged  A  portable  battery  should  have  a  greater  specific 
gravity,  and,  when  fully  charged,  this  will  vary  from  1.275  to 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        245 

1.300.  If  too  low,  add  stronger  sulphuric  acid  until  the  correct 
specific  gravity  is  obtained. 

Water  must  be  occasionally  added  to  the  electrolyte  to  make  up 
for  evaporation.  When  water  is  added,  this  should  be  poured  to 
the  bottom  of  the  cell  through  a  long  rubber  tube  attached  to  a 
funnel.  The  electrolyte  level  should  be  about  %  in.  above  the 
plates. 

If  a  storage  battery  is  to  remain  unused  for  any  length  of  time, 
it  should  be  discharged  and  immediately  recharged  about  once  per 


FIG.  237. — Battery  hydrometer. 

week.  To  allow  a  storage  battery  to  remain  discharged  for  any 
length  of  time  is  injurious  to  the  plates. 

The  Edison  or  Nickel-iron  Storage  Battery. — The  Edison 
storage  battery  consists  of  two  sets  of  sheet-steel  plates  or  grids, 
submerged  in  an  electrolyte  of  caustic  potash.  The  plates  or 
grids  support  tubes  and  pockets  containing  the  active  materials 
(Fig.  238).  These  grids  have  holes  at  the  top  which  fit  snugly 
over  connecting  rods  on  which  the  poles  are  forced  by  pressure  to 
a  perfect  fit.  The  plates  are  held  apart  by  spacing  washers  on 
the  connecting  rod.  The  positive  plates  are  assembled  on  one 
connecting  rod  with  the  positive  pole  and  the  negative  plates  on  a 
similar  rod  with  the  negative  pole. 

The  positive  material  of  the  positive  plate  is  nickel  hydrate. 
When  the  cell  is  charged,  the  nickel  hydrate  changes  to  a  high 
oxide  of  nickel. 


246 


FARM  MOTORS 


The  active  material  on  the  negative  plate  is  a  specially  prepared 
black  oxide  of  iron. 

The  plates  are  held  in  a  steel  container  which  eliminates 
the  danger  of  broken  jars.  Hard-rubber  insulation  at  the  bot- 
tom and  sides  prevents  electrical  contact  between  plates  and 
container. 

Edison  batteries  do  not  have  as  high  capacity  when  new  as 


CAP 


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^•SPACING  WSHER 
\--CONNCCTJNGROD 
M- POSITIVE GRID 
N-  GRID  SEPARATOR 
0  -SEAMLESS 

•  STEEL  RINGS 
?•  POSITIVE  TUBE 
(MCKEL  HYDRATE  &\ 
\NICKEL  IN  LAYERS  / 


-CORRUGATIONS 


•SUSPENSION  BOSS 


CELL  BOTTOM  - 
(WELDED  TO  SIDES) 


FIG.  238. — Edison  storage  battery. 


after  some  weeks  of  use.  This  is  due  to  the  improvement  of 
conditions  in  the  nickel  electrode,  brought  about  by  regular  charg- 
ing and  recharging. 

The  voltage  of  an  Edison  cell  when  fully  charged  is  less  than  2 
volts,  while  that  of  the  lead  cell  is  more  than  2  volts.  This  means' 
that  more  Edison  cells  will  be  require^  for  a  given  voltage  than 
lead  cells. 

The  cost  of  Edison  cells  and  of  the  best  grades  of  lead  cells  is 
about  the  same.  The  cost  of  an  Edison  battery  for  higher  volt- 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        247 

ages  is  greater  than  that  of  lead  batteries  as  the  necessary  number 
of  cells  for  a  given  voltage  is  greater  in  an  Edison  battery. 

The  Edison  cell  has  a  tight  cover,  a  valve  being  provided 
for  the  escape  of  gas.  Very  little  water  is  lost  by  ordinary 
evaporation. 

The  normal  strength  of  the  electrolyte  is  1.200,  as  measured  by 
a  hydrometer,  but  may  at  times  be  as  high  as  1.230. 

Methods  of  Connecting  Batteries.  —  The  various  methods  of 
connecting  batteries  are  illustrated  in  Figs.  239  to  241. 


ABC 

FIG.  239.  —  Batteries  in  series. 


In  the  series  battery  connection  (Fig.  239)  the  positive  (-f) 
of  one  cell  is  connected  to  the  negative  (  —  )  of  the  other  cell. 
The  voltage  of  the  battery  is  equal  to  the  sum  of  the  voltage  of  the 


+  Terminal 


—  rermfnctf 


FIG.  240.  —  Batteries  in  multiple. 

cells  A,  B,  and  C,  while  the  current  is  equal  to  that  of  one  cell 
only.  If  three  storage  cells,  each  having  a  pressure  of  2.1  volts 
are  connected  in  series,  the  pressure  of  the  battery  is  6.3  volts. 


FIG.  241.  —  Batteries  in  multiple-series. 

The  multiple-battery  connection  method  is  illustrated  in  Fig. 
240.  In  this  case  the  positive  terminals  are  connected,  as  are  also 
all  the  negative  terminals  of  the  battery.  If  the  external  resist- 
ance is  low,  the  current  of  the  battery  is  proportional  to  the 
number  of  cells,  while  the  pressure  in  volts  is  equal  to  that  of  one 
cell  only. 

Another  method  shown  in  Fig.  241  and  called  the  multiple- 


248  FARM  MOTORS 

series  method  of  connecting  batteries  consists  of  connecting  the 
battery  in  two  sets,  the  cells  of  each  set  being  connected  in  series 
and  the  two  sets  are  connected  in  multiple.  The  effect  of 
this  method  of  connecting  cells  is  that  the  total  pressure  of  the 
system  is  equal  to  that  of  three  cells  and  the  current  is  equal  to 
that  of  two  cells. 

The  Electric  Generator. — The  electric  generator,  popularly 
called  a  dynamo,  consists  essentially  of  an  armature  composed 
of  coils  of  wire  wound  around  an  iron  core,  and  one  or  more  mag- 
nets. Either  the  armature  or  the  magnets  must  be  given  motion 
by  some  form  of  motor  with  relation  to  the  other  before  the  gen- 
erator can  generate  a  current  of  electricity. 

The  magnet  may  be  a  permanent  magnet  or  an  electromagnet. 
The  so-called  "permanent  magnet"  is  made  of  hard-tempered  steel 
which,  after  having  been  brought  under  the  influence  of  some  mag- 
netizing apparatus,  will  retain  a  certain  amount  of  magnetism. 
Permanent  magnets  are  expensive  to  make  in  large  sizes  and  do  not 
hold  their  magnetism  for  any  length  of  time.  They  are  employed 
only  in  the  construction  of  small  electric  generators  called 
magnetos,  which  are  used  mainly  in  connection  with  electric 
ignition  systems  for  gas  engines,  and  for  signaling  work. 

Generators  which  generate  electric  current  for  commercial 
purposes  employ  electromagnets.  An  electromagnet  consists  of 
a  piece  of  iron  which  has  wound  around  it  many  turns  of  insulated 
copper  wire.  If  a  current  of  electricity  is  passed  through  the 
insulated  copper  wire,  the  iron  becomes  immediately  magnetized, 
and  remains  magnetized  as  long  as  the  current  is  passing  through 
the  wire.  There  is  practically  no  limit  to  the  strength  of  an  elec- 
tromagnet, as  this  depends  only  on  the  number  of  turns  of 
copper  wire  and  on  the  current  passing  through  the  wire,  or  on  the 
ampere-turns. 

Action  of  the  Electric  Generator. — The  action  of  a  generator 
depends  on  the  fact  that  when  a  wire  or  other  conductor  of  elec- 
tricity is  moved  between  the  poles  of  a  magnet,  electrical  pressure 
is  induced  in  the  conductor.  In  the  simple  electric  generator,  an 
armature  consisting  of  only  one  coil  of  wire  is  rotated  between 
the  north  and  south  poles  of  a  magnet.  The  ends  of  the  coil  are 
connected  to  two  insulated  rings  mounted  on  a  shaft  which  gives 
rotary  motion  to  the  coil.  If  two  brushes  are  allowed  to  bear  on 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        249 

the  two  rings  and  are  connected  to  a  measuring  instrument,  it  will 
be  noticed  that  the  current  will  flow  in  one  direction  during  half 
of  a  revolution  and  in  the  other  direction  during  the  next  half  of  a 
revolution.  If  the  readings  of  the  instrument  are  recorded  graph- 
ically, a  curve  like  Fig.  242  will  be  obtained.  In  this  curve  the 
horizontal  distances  represent  the  angles  turned,  while  in  the 
vertical  distances  are  recorded  values  of  electrical  pressure  in  volts 
which  cause  a  corresponding  flow  of  electric  current  at  the  various 


FIG.  242. — Alternating  current. 

angular  positions.  It  will  be  noticed  that  the  current  starts  at 
zero,  and  increases  to  a  maximum  during  one-quarter  turn.  At 
the  half  turn  it  is  zero  again.  After  half  of  a  revolution  the 
direction  of  the  current  reverses,  attains  a  negative  maximum  at 
three-quarters  of  a  turn  and  then  is  again  diminished  to  zero. 

Direct  and  Alternating  Currents. — The  action  of  the  simple 
generator,  explained  in  the  last  section,  produces  an  alternating 
current,  which  varies  from  a  maximum  to  a  minimum,  first 
in  one  direction  and  then  in  the  other.  In  the  actual  electric 
generator  there  are  many  conductors  in  the  armature  and  several 
sets  of  poles,  so  that  as  the  armature  revolves,  the  current  reverses 
its  direction  many  times  a  second.  For  long-distance  electric 
transmission  this  type  of  electric  current  usually  is  used,  as 
alternating  currents  can  be  generated  at  very  high  voltage,  and 
these  voltages  can  be  increased  or  decreased  at  pleasure  by  means 
of  simple  instruments  called  transformers.  There  are,  however, 
certain  uses  to  which  the  alternating  form  of  electric  current 
cannot  be  put.  One  case  was  mentioned  in  connection  with  the 
charging  of  storage  batteries,  where  a  direct  current  must  be  used, 
the.  chemical  action  necessary  in  a  storage  battery  being  an 
impossibility  with  an  alternating  current. 

Direct  current  is  generated  in  a  generator  by  the  addition  of  a 


250 


FARM  MOTORS 


commutator  shown  in  Fig.  243,  which  consists  of  a  set  of  seg- 
ments insulated  from  each  other  and  from  the  armature  shaft,  and 
which  rectify  the  current  by  shifting  the  position  of  the  brushes 
with  respect  to  the  armature  coils.  The  principle  of  the  commu- 

tator  can  be  seen  from  Fig.  244.     R  is 

a  split  ring  to  the  two  segments  of 
which  are  fastened  the  two  ends  of  the 
coil,  explained  in  connection  with  the 
working  of  the  simple  dynamo.  The 
two  brushes  BC  are  connected  to  two 
wires  carrying  off  the  current  to  the 
external  circuit.  As  the  coil  of  the 
simple  armature  gets  into  the  vertical 
position  between  the  poles  of  the 
magnet  each  brush  changes  from  the 
segment  with  which  it  was  in  contact 
to  the  other,  so  that  the  effect  is  just 
the  same  as  if  the  brushes  were  inter- 
changed, and  the  current  generated 
during  the  second  half  of  the  revolution 

FIG.  243.— Commutator.     flows  in  *he  same  direction  round  the 
external  circuit  as  the  preceding  current 

did.  The  current,  although  generated  in  the  reverse  direction, 
enters  the  external  circuit  at  the  other  end,  and  the  result  is  a 
unidirectional  current.  This  is  changed  into  a 
direct  current  by  the  employment  of  an  armature 
with  a  large  number  of  coils  and  a  commutator 
of  many  segments. 

Principal  Parts  of  Generators  and  Motors. 
— The  principal  parts  of  all  dynamo — electric 
machinery,  whether  they  be  generators  of  elec- 
tricity or  motors  driven  by  electric  current,  are : 

1.  A  magnetic  field,  commonly  called  a  field, 
whose  function  it  is  to  furnish  magnetic  lines.  In  the  earlier 
machines  this  consisted  of  a  two-pole  magnet  but  the  modern 
generators  and  motors  are  provided  with  four  or  more  poles.  The 
reason  for  this  is  that  a  more  compact  machine  can  be  produced. 
A  generator  whose  field  consists  of  a  two-pole  magnet  is  called 
a  bipolar  generator,  while  one  with  a  magnet  consisting  of  four 
or  more  poles  is  called  a  multipolar  generator. 


FIG.  244.— 
Principle  of  the 
commutator. 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        251 


2.  An  armature  which  is  made  up  of  insulated  windings  of 
copper  wire  on  an  iron  core.     The  function  of  the  armature  is  to 
cut  the  magnetic  lines  of  force  furnished  by  the  field.     In  all 
direct-current  machines  the  field  is  the  stationary  part  while  the 
armature  revolves.     In  alternating-current  machines,  the  field 
is  the  revolving  part  in  all  but  the  very  small  machines. 

3.  A  device  which  collects  or  delivers  current  to  the  armature, 
depending  on  whether  the  machine  is  a  generator  or  a  motor. 
In  the  case  of  alternating-current  generators  and  motors  this  is 
accomplished  by  brushes  pressing  on  collector  rings,  if  the  arma- 
ture is   the  revolving   element.     In   larger   alternating-current 


FIG.  245. — Parts  of  dynamo-electric  machinery. 

machines  where  the  armature  is  the  stationary  part,  the  current 
is  taken  away  from  or  delivered  to  the  windings  by  leads  entering 
the  frame  of  the  dynamo  or  motor.  When  dealing  with  direct- 
current  machines,  current  is  delivered  to  or  taken  away  from  the 
armature  by  brushes  pressing  on  a  commutator  whose  function, 
as  explained  in  the  earlier  part  of  this  chapter,  is  also  to  change 
the  alternating  current  into  direct  current. 

4.  A  shaft  passing  through  the  revolving  part,  which  is  con- 
nected to  the  engine  furnishing  power  in  the  case  of  the  generator 
and  to  the  machine  to  be  driven  in  the  case  of  the  electric  motor. 

5.  A  frame,  usually  made  of  cast  iron,  whose  function  it  is 
to  support  the  bearings  in  which  the  shaft  of  the  generator  or 
mctor  revolves. 


252  FARM  MOTORS 

The  various  parts  of  a  direct-current  generator  or  motor  are 
illustrated  in  Fig.  245.  The  field  and  armature  of  an  alternating- 
current  generator  are  illustrated  in  Figs.  246  and  247  respectively. 

Classification  of  Generators  and  Motors. — The  first  broad 
classification  is  into  direct-  and  alternating-current  generators 
and  motors. 

Direct-current  generators  and  motors  are  divided  into  three 
classes  depending  on  the  type  of  field  winding  as  series-wound, 
shunt-wound,  and  compound-wound.  For  simplicity  these 
three  types  are  represented  as  bipolar  machines  in  Figs.  248, 
249,  and  250. 

Series-wound  Generators. — In  the  series-wound  dynamo,  illus- 
trated by  Fig.  248,  one  end  of  the  field  winding  is  connected  to 
the  positive  brush  and  the  other  to  the  external  circuit.  The 
action  of  the  series-wound  machines  depends  on  the  fact  that  the 
soft  iron  poles  retain  sufficient  magnetism  to  send  out  a  current 
to  the  external  circuit  when  the  armature  is  rotated.  The  entire 
current  passing  through  the  field,  the  electromagnet  of  the  field 
increases  in  strength  as  the  current  developed  by  the  generator 
becomes  greater.  Series-wound  generators  are  used  mainly  to 
supply  electricity  to  direct-current  arc  lamps. 

Series-wound  Motors. — The  series-wound  motor  has  a  winding 
similar  to  that  of  the  series-wound  generator.  In  fact,  it  is 
difficult  to  tell  the  difference  between  any  direct-current 
motor  and  generator,  the  electrical  features  being  the  same. .  A 
series- wound  generator  when  operated  as  a  motor  will  run  in  re- 
verse direction.  The  series-wound  motor  is  used  for  work  where 
hand  control  can  be  used  as  in  the  operation  of  hoists,  cranes, 
and  for  the  propulsion  of  electric  cars.  A  series-wound  motor  can 
be  started  at  full-load  and  should  never  be  used  where  there  is  a 
possibility  for  the  load  to  be  removed  suddenly.  A  series-wound 
motor  will  "run  away";  that  is,  its  speed  will  increase  to  such  an 
extent  that  it  may  be  destroyed  by  centrifugal  force,  if  the  load 
is  removed.  For  this  reason  it  is  not  safe  to  use  belt  drives  with 
series-wound  motors.  A  series  motor  is  illustrated  in  Fig.  249. 

Shunt-wound  Generators. — The  principle  of  a  shunt-wound 
generator  is  illustrated  in  Fig.  249.  The  field  winding  consists 
of  a  great  number  of  turns  of  very  fine  wire.  Both  ends  of  the 
field  winding  are  connected  to  the  brushes  of  the  generator. 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        253 


FIG.  246. — Field  of  alternating-current  generator. 


FIG.  247. — Armature  of  alternating-current  generator. 


FIG.  248. — Series-       FIG.  249. — Shunt-wound      FIG.  250. — Compound- 
wound  dynamo,  dynamo.  wound  dynamo. 


254  FARM  MOTORS 

Since  the  field  winding  is  very  small  in  comparison  with  the  line 
wire,  only  a  small  part  of  the  current  flows  around  the  field  coils. 
This  type  of  generator  is  used  for  charging  storage  batteries.  A 
shunt- wound  generator  will  supply  constant  voltage  provided  the 
load  does  not  vary  much. 

Shunt-wound  Motors. — The  shunt-wound  motor  has  the  same 
type  of  winding  as  the  shunt-wound  generator.  Shunt-wound 
motors  are  used  for  all  kinds  of  work  where  fairly  constant  speed 
is  desired.  A  well-designed  shunt-wound  motor  will  not  vary 
much  in  speed  with  a  variable  load.  In  starting  a  shunt-wound 
motor  it  is  necessary  to  put  considerable  resistance  in  series  with 
the  field  of  the  motor.  This  is  due  to  the  fact  that  the  resistance 
of  the  armature  of  a  shunt- wound  motor  is  very  low.  If  a  volt- 
age of  from  110  to  220  volts  is  allowed  to  pass  through  an  arma- 
ture of  low  resistance,  an  enormous  current  would  flow  through 
the  armature  in  starting,  which  would  result  in  injury  to  the 
armature  coils,  and  also  to  the  commutator  by  excessive  spark- 
ing. By  putting  a  resistance  in  series  with  the  armature  the 
current  which  is  allowed  to  pass  through  it  is  decreased.  Then, 
as  the  motor  begins  to  speed  up,  the  armature  turning  between 
poles  of  a  magnet,  produces  a  generator  action  which  sends  an 
electrical  pressure  in  opposition  to  that  which  is  sent  in  from  the 
mains.  This  tends  to  reduce  the  current  passing  through  the 
armature  to  a 'safe  limit.  In  connection  with  this,  it  must  be 
remembered,  that  weakening  the  field  of  a  shunt-wound  motor, 
reduces  the  above-mentioned  generator  action,  and  speeds  up  the 
motor.  A  break  in  the  field  connection  of  a  shunt-wound  motor, 
while  it  is  in  operation,  may  result  in  considerable  damage  by 
overspeeding. 

Compound-wound  Generators. — The  compound-wound  gen- 
erator is  used  extensively  for  the  generation  of  current  for  all 
purposes,  including  that  for  light,  power  and  street-car  propul- 
sion. The  voltage  of  this  type  of  machine  is  automatically 
regulated  by  a  combination  of  a  shunt  and  series  winding.  This 
type  of  winding  is  illustrated  in  Fig.  250.  A  large  portion  of  the 
field  is  wound  with  many  turns  of  fine  insulated  wire,  which  must 
produce  a  field  of  sufficient  strength  to  generate  the  rated  volt- 
age of  the  generator  when  no  load  is  placed  on  it.  A  series  wind- 
ing of  several  turns  of  heavy  wire  is  wound  over  the  shunt  wind- 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        255 

ing.  This  series  winding  adds  sufficient  strength  to  the  field  so  as 
to  develop  the  standard  voltage  at  the  maximum  load  of  the 
generator.  In  some  com  pound- wound  generators,  the  series 
winding  is  arranged  to  increase  the  voltage  slightly  as  the  load 
increases,  and  to  compensate  for  loss  in  voltage  during  trans- 
mission. 

Compound-wound  Motors. — The  compound-wound  motor  has 
a  series  and  shunt  winding  like  the  compound-wound  generator. 
It  is  used  mainly  for  the  driving  of  machines  where  very  close 
speed  regulation  is  essential,  such  as  printing  presses,  machine 
tools,  and  looms. 

Various  Types  of  Motors  Compared. — For  most  purposes, 
the  shunt-wound  motor  is  very  satisfactory,  and,  being  much 
cheaper  than  the  compound-wound  motor,  it  is  used  for  the  driv- 
ing of  all  kinds  of  machinery  which  can  be  started  at  no-load. 
If  motors  are  to  be  used  for  pumping,  the  series- wound  or  com- 
pound-wound motor  should  be  selected,  unless  a  clutch  can  be 
inserted  between  the  motor  and  the  pump. 


t  0  0  C/O  0  0  „' 


—  B 

FIG.  25"1.  —  Parallel  system  of  distribution. 

Distribution  of  Electric  Current.  —  Electricity  may  be  dis- 
tributed as  direct  or  as  alternating  current.  Direct  current 
usually  is  used  for  short-distance  distribution,  the  most  common 
voltages  being  110  and  220  volts.  If  the  furthest  point  of  the 
distributing  system  is  a  mile  or  further  from  the  dynamo  it  is 
well  to  use  alternating  currents-  in  order  to  reduce  the  cost  of 
wire.  Alternating  currents  are  used  in  voltages  of  1,100,  2,200, 
4,400,  6,600,  and  higher. 

When  using  direct  currents  the  parallel  system  of  distribution 
is  most  common.  The  principle  of  this  system  is  illustrated  in 
Fig.  251.  The  feeders  A  and  B  lead  from  the  generator  D  to  the 
switchboard.  The  mains  EF  and  GH  connect  the  feeders  with 
the  branches  which  supply  current  for  lamps,  motors,  etc. 

In  another   system  of  direct-current   distribution,  the  series 


256 


FARM  MOTORS 


shown  in  Fig.  252,  the  lamps  are  connected  in  series  with  the 
generator  D.  This  system  is  very  seldom  used  at  the  present 
time,  and  then  only  for  supplying  current  to  direct-current 
street  arc  lamps. 


FIG.  252. — Series  system  of  distribution. 

Electric  Meters. — The  four  most  important  quantities  which 
must  be  known  are:  current,  voltage  or  electrical  pressure,  resist- 
ance and  power.  Then  most  switchboards  are  also  provided 
with  ground  detectors  for  the  purpose  of  telling  when  the  circuit 
is  grounded. 


FIG.  253. — Ammeter. 


FIG.  254.— Voltmeter. 


Electric  current  is  measured  by  an  instrument  called  an  amme- 
ter, and  illustrated  by  Fig.  253.  This  instrument  usually  con- 
sists of  a  coil  of  wire  between  the  poles  of  a  permanent  magnet. 
The  current  to  be  measured  is  sent  through  the  coil,  this  produc- 
ing a  movement  of  the  coil  which  is  recorded  by  a  needle  on  a 
graduated  scale. 

A  voltmeter,  illustrated  in  Fig.  254,  is  used  for  measuring  elec- 
tric pressure.  This  instrument  differs  from  the  ammeter  in  that 
a  resistance  is  placed  in  series  with  the  coil,  otherwise  the  volt- 
meter and  ammeter  for  the  measurement  of  direct  current  are 
alike. 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        257 

For  the  measurement  of  voltage  and  current  of  batteries  a 
battery  meter  illustrated  in  Fig.  255  is  used. 

The  method  of  connecting  an  ammeter  M  and  a  voltmeter  V 
to  a  circuit  is  shown  in  Fig.  256.  AB  and  CD  are  the  two  wires 
of  the  circuit. 

Resistance  can  be  measured  by  using  a  voltmeter  and  an 
ammeter  together.  The  ammeter  is  connected  in  series  with 
the  resistance,  while  the  voltmeter  is  connected  to  the  terminals. 
The  resistance  can  then  be  calculated  by  Ohm's  law,  explained 


Bj 


FIG.  255.— Battery  meter.         FIG.  256.- 


-Method  of  connecting  ammeter 
and  voltmeter. 


in  the  beginning  of  this  chapter.     If  7  is  the  ammeter  reading 
and  E  is  the  voltmeter  reading  the  resistance  is 


An  instrument  which  measures  the  electrical  power  of  a  cir- 
cuit is  called  a  wattmeter.  Since  the  power  of  a  direct-current 
circuit  is  the  product  of  the  current  flowing  through  the  circuit  by 
the  voltage  between  the  terminals,  the  power  can  be  obtained 
by  taking  the  product  of  the  voltmeter  and  ammeter  readings  of 
any  circuit.  In  alternating-current  circuits  this  product  \  of  the 
voltmeter  and  ammeter  readings  does  not  give  the  true  electric 
power  of  the  circuit  and  a  wattmeter  must  be  used.  Direct-  and 
alternating-current  wattmeters  are  illustrated  in,  Figs.  257 
and  258  respectively. 

Fuses  and  Circuit-breakers.  —  The  function  of  fuses  and  of 
circuit-breakers  is  to  protect  electric  machines,  appliances  and 

17 


258 


FARM  MOTORS 


FIG.  257. — Direct-current  wattmeter. 


FIQ.  258. — Alternating-current  wattmeter. 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        259 


wires  from  being  traversed  by  currents  above  their  safe  carrying 
capacities. 

Fuses  are  made  of  an  alloy  of  lead  and  zinc.     For  temporary 
connections  fuse  wire  is  used.     A  better  method  is  to  solder  the 


FIG.  259. — Fuse. 


FIG.  260. — Edison  plug  cutout  and  fuse. 


FIG.  261.— Enclosed-type  fuse  and  fuse-block. 


Flu.  262. — Circuit  breakers. 

wire  to  copper  terminals  as  shown  in  Fig.  259.     The  Edison  plug 
cutout  and  fuse,  illustrated  in  Fig.   260,  is  very  convenient. 
Another  form,  the  inclosed  type  of  fuse,  is  shown  in  Fig.  261. 
Due  to  the  uncertainty  and  unreliability  of  fuses,  circuit- 


260  FARM  MOTORS 

breakers  are  employed  for  the  protection  of  lines  carrying  heavy 
currents. 

Several  forms  of  circuit-breakers  are  illustrated  in  Fig.  262.  A 
circuit-breaker  is  a  switch  which  opens  automatically  where  the 
current  passing  through  it  is  greater  than  that  for  which  it  is 
set.  Circuit-breakers  are  made  to  open  either  one  or  both  sides 
of  the  circuit  and  are  named  accordingly  single-pole  and  double- 
pole  circuit-breakers  respectively. 

Switches  and  Rheostats. — The  functions  of  a  switch  and  rheo- 
stat in  an  electrical  circuit  are  analogous  to  that  of  a  valve  in  a 


'MllHIHirnilirH  9HBHB  ajm 

«~:#* 


FIG.  263.— Switches. 

steam  or  water  line.     The  switch  opens  or  closes  the  circuit  while 
the  rheostat  regulates  the  strength  of  the  current  passing. 

For  controlling  the  flow  of  small  currents  in  connection  with 
the  illumination  of  rooms,  some  form  of  snap  switch  or  push- 
button switch  is  '  employed.  These  switches  can  be  made  to 
control  the  current  from  two,  three,  or  four  different  places.  A 
special  form  of  push-button  or  snap  switch,  called  the  electrolier 
switch,  can  be  used  for  turning  on  part  or  all  of  the  lamps  on  an 
electric-light  chandelier.  Thus  in  the  case  of  a  four-light  chande- 
lier, this  -type  of  switch  can  be  wired  so  that  the  burning  of  one, 
two,  tliree,  or  all  of  the  lamps  can  be  controlled  from  the  wall  of  the 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        261 

room.     Several  forms   of  snap   and   push-button   switches   are 
illustrated  in  Fig.  263. 

For  currents  above  25  amp.  a  knife  switch  should  be  em- 
ployed. This  type  of  switch  has  a  contact-making  piece  of  a 
shape  somewhat  like  a  knife.  A  single-pole  knife  switch  opens 


FIG.  264. — Knife  switches. 

only  one  side  of  a  circuit,  a  double-pole  two  sides,  etc.  Double- 
throw  switches  are  used  when  one  of  two  circuits  has  to  be  con- 
trolled at  a  time.  Several  forms  of  knife  switches  are  illus- 
trated in  Fig.  264. 


FIG.  265. — Rheostats. 

A  rheostat  for  controlling  the  strength  of  electric  current  is 
illustrated  in  Fig.  265.  The  fundamental  parts  of  a  rheostat 
are:  coils  of  iron  wire  to  absorb  electric  current,  metallic  points 
connecting  the  various  coils  to  the  outside,  and  an  arm  which  is 
moved  over  the  various  points. 


262 


FARM  MOTORS 


Method  of  Connecting  Motors. — The  method  of  connecting 
a  shunt  motor  and  its  starting  box  to  the  circuit  is  illustrated 
in  Fig.  266.  A  and  B  are  the  two  leads  which  bring  the  current 
from  the  mains  (connected  to  a  generator)  through  the  fuses  P, 
R  and  to  the  switch  S.  One  terminal  of  the  switch  L  is  connected 
to  the  field  F  and  to  the  armature  G  of  the  motor.  The  other 


FIG.  266. — Method  of  connecting 
motors. 


FIG.  267. — Motor-driven  pump. 


terminal  K  leads  to  the  starting  box.  The  handle  H  of  the  start- 
ing box  is  connected  with  the  terminal  E,  which  is  attached  to  the 
armature  of  the  motor.  The  other  terminal  D  of  the  starting 
box  is  connected  with  the  field  of  the  motor  F. 

When  the  motor  is  to  be  started,  the  switch  S  is  closed  and  the 
handle  H  is  on  the  contact  point  1.  The  handle  H  is  then 
moved  slowly  to  the  right.  When  the  handle  H  is  on  the  last 
contact  point,  it  is  held  in  position  by  the  magnet  M.  To  stop 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        263 

the  motor,  the  switch  S  is  opened.  The  magnet  M,  losing  its 
magnetism,  allows  a  spring  to  bring  back  the  arm  H  to  the  start- 
ing point. 

The  Electric  Motor  on  the  Farm. — The  electric  motor  is  well- 
suited  for  most  farm  work  which  is  accomplished  by  the  small 


FIG.  268. — Motor-driven  washing  machine. 

stationary  gasoline  engine.  It  is  not  as  portable  in  any  but  the 
very  small  sizes,  but  possesses  other  advantages  for  certain 
uses.  A  small  electric  motor  requires  no  special  foundation  and 
may  be  placed  on  the  floor,  on  a  truck,  or  may  be  fastened  to 
the  wall  or  ceiling,  is  easily  started  and  requires  less  care  than 
the  gasoline  engine.  The  cleanliness  of  the  electric  motor  and 


264 


FARM  MOTORS 


the  absence  of  offensive  fumes  make  it  more  desirable  for  use 
in  the  house,  the  dairy  and  the  barn. 

Some  of  the  uses  of  the  electric  motor  in  the  home  are  illus- 
trated in  Figs.  267  to  269.  The  house  pump  driven  by  a  motor  of 
%  hp.  is  shown  in  Fig.  267.  Another  electric  motor  of  Jfo  hp. 
drives  a  washing  machine  illustrated  in  Fig.  268.  Still  a  smaller 


FIG.  269. — Motor-driven  sewing  machine. 

motor  is  shown  connected  to  a  sewing  machine  in  Fig.  269.  Other 
uses  to  which  the  electric  motor  can  be  put  in  the  farm  house- 
hold may  be  mentioned :  the  driving  of  fans  during  hot  weather, 
of  vacuum  cleaners,  of  ice-oream  freezers,  of  cream  separators, 
of  churns,  of  milking  machines  and  of  grindstones.  An  electric 
motor  can  also  be  used  for  the  shelling  and  grinding  of  feed  arid 
for  the  many  operations  in  the  farm  shop. 

For  outdoor  use  and  for  the  heavier  farming  operations  the 
electric  motor  is  not  as  suitable  as  the  gasoline  engine. 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        265 

The  Farm  Electric -light  Plant. — For  farms  of  the  average 
size,  which  do  not  have  the  advantages  of  cheap  power  from 
a  nearby  transmission  system,  private  electric-lighting  plants 
driven  by  gasoline  engines  are  becoming  quite  common. 

When  an  electric-light  plant  is  to  supply  current  for  lighting 
only,  the  complete  installation,  including  the  wiring  of  an  average 
eight-room  house  and  barn  will  vary  from  $350  to  $750.  If  the 


FIG.  270. — Farm  electric-light  plant. 

plant  is  to  supply  current  for.  motors  as  well  as  for  lights  the  first 
cost  will  be  from  $1,200  up,  depending  on  the  size  of  motors 
used.  The  cost  of  operating  a  plant  for  lighting  only  will  usually' 
be  about  $15  a  year.  The  cost  of  operating  plants  which  supply 
electricity  for  power  will  depend  on  the  size  of  motors  and  on  the 
amount  of  work  done. 

The  essential  parts  of  a  private  electric-light  plant  are: 

1.  A  gasoline  engine  and  an  electric  generator. 

2.  A  set  of  storage  batteries  for  storing  the  electricity  to  be 
used  when  wanted  and  which  supplies  a  steady  light  whether 
the  engine  is  running  or  not. 


266 


FARM  MOTORS 


3.  A  switchboard  with  an   ammeter,  a  voltmeter,  fuses   and 
switches   to  control  the  operation  of  the  dynamo  and  of  the 
storage  battery. 

4.  Wires  from  the  switchboard  to  the  house,  barn  and  other 
places  where  electricity  is  to  be  used. 

5.  Wiring  of  the  house,  barn,  etc. 

In  Fig.  270  is  illustrated  a  farm  electric-light  plant. 


PUSH  ROD  ADJUSTHEN T 
LIGHT ANDPQWER  SWfTQt 

STOPPING  SWITCH 
SPARK  PLUG 

STARTING  SWITCH 


FIG.  271. — Engine  and  generator  for  farm  electric-light  plant. 

The  use  of  the  private  electric-light  plant  for  farms  of  average 
size  was  out  of  the  question  until  quite  recently  on  account  of  the 
great  cost  of  the  storage  battery.  With  the  ordinary  carbon 
lamps  operating  at  110  volts,  about  60  storage  cells  were  required 
to  maintain  the  correct  voltage  when  the  engine  was  not  running. 
The  development  of  the  tungsten  lamp,  which  operates  satis- 
factory at  about  30  volts,  necessitates  the  use  of  a  battery  of  only 
17  cells,  and  has  the  added  advantage  of  greater  safety  from 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        267 

short-circuits.  Then  the  tungsten  lamp  consumes  only  about 
one-third  of  the  electric  energy  required  by  the  carbon  lamp  of 
the  same  candlepower. 

Installation  of  Electric  Motors  and  Generators. — A  dry,  cool 
and  clean  place,  free  from  dust,  should  be  chosen  for  the  location 
of  an  electric  machine.  If  the  surrounding  air  is  warm,  the  tem- 
perature of  the  various  parts  is  likely  to  rise  to  a  sufficient  degree 
to  endanger  armature,  or  field,  or  both. 

If  a  motor  has  to  be  located  in  a  dusty  place,  or  in  connection 


FIG.  272. — Enclosed-type  motor. 

with  farming  operations  where  particles  of  feed  or  trash  may  lodge 
on  the  motor,  an  inclosed  type  like  the  one  shown  in  Fig.  272 
should  be  selected. 

In  locating  motors  or  generators  care  should  be  taken  to  pro- 
vide easy  access  to  all  parts.  Also  sufficient  distance  must  be 
allowed  between  the  pulley  centers  of  the  driver  and  driven. 

A  substantial  foundation  of  timber,  brick,  or  concrete  should 
be  provided  for  all  motors  and  dynamos  above  25  hp.  Small 
machines  can  be  fastened  to  the  floor  and  require  no  special 
foundation. 

If  an  electric  machine  has  been  exposed  to  changes  of  climate, 


268  FARM  MOTORS 

it  should  be  kept  in  a  warm,  dry  place  for  several  days,  as  the 
insulation  always  absorbs  dampness  which  can  be  only  slowly 
dried  out. 

Small  machines  usually  are  shipped  complete  and  ready  to 
run.  Large  motors  and  generators  usually  are  shipped  in  boxes, 
"knocked  down,"  as  this  reduces  freight  charges.  . 

In  assembling  parts,  all  connections  and  parts  should  be  wiped 
perfectly  clean  and  free  from  grit.  The  bearing  sleeves  and  oil 
rings  should  be  placed  in  position  on  the  shaft  before  the  armature 
is  lowered  in  place. 

The  bearings  should  be  filled  with  a  good  grade  of  thin  lubri- 
cating oil,  care  being  taken  not  to  fill  the  oil  cellars  so  they  will 
overflow. 

In  clamping  the  brushes  in  place,  they  should  be  adjusted  so 
that  the  pressure  on  the  commutator  is  about  1J^  Ib. 

The  brushes  are  fitted  to  the  commutator  by  passing  beneath 
them  No.  0  sandpaper,  the  rough  side  against  the  brush  and  the 
smooth  side  held  down  closely  against  the  surface  of  the  commu- 
tator. The  sandpaper  should  be  moved  in  the  direction  of  rota- 
tion of  the  armature,  and  on  drawing  it  back  for  the  next  cut, 
the  brush  should  be  raised  so  as  to  free  it  from  the  sandpaper. 
It  is  then  lowered  and  repeated  until  a  perfect  fit  is  obtained  be- 
tween the  brush  and  commutator. 

Starting  and  Stopping  Motors. — Before  starting  a  machine 
for  the  first  time,  care  must  be  taken  that  all  set  screws  and  nuts 
are  tight  and  that  the  oiling  system  works  properly.  The  arma- 
ture is  then  turned  by  hand  to  see  that  it  is  free  and  does  not  rub 
or  bind  at  any  point.  The  wiring  should  be  carefully  gone  over 
and  all  terminals  screwed  down  tightly.  When  everything  is  in 
good  condition,  the  switch  is  closed,  but  before  doing  this  one 
must  make  certain  that  the  starting-box  handle  is  in  the  "off" 
position.  After  the  switch  is  closed,  the  handle  on  the  rheo- 
stat is  moved,  gradually  cutting  out  the  resistance  as  the  motor 
speeds  up. 

It  is  well  to  run  a  new  motor  for  a  time  before  putting  on  the  load. 

In  stopping  a  motor,  pull  the  switch  and  the  handle  of  the 
starting  rheostat  should  fly  back  to  the  "off"  position. 

Starting  and  Stopping  Generators. — The  general  rules  in  regard 
to  starting  an  electric  machine  are  alike  for  the  generator  and 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        269 

motor.  When  the  generator  is  ready  to  be  started,  place  the 
driving  belt  on  the  pulley  of  the  armature  shaft  and  start  the 
engine  driving  the  generator,  bringing  the  machine  up  to  speed 
very  slowly. 

Generators  usually  are  tested  before  they  leave  the  factory. 
As  a  rule,  generators  will  retain  sufficient  magnetism  in  their 
fields  so  they  can  be  started.  Sometimes  a  generator  loses  its 
field  magnetism  on  the  way  from  the  factory  to  its  destination. 
The  fields  can  be  magnetized  by  current  from  a  battery  or  from 
another  dynamo. 

If  a  generator  is  supplying  incandescent  lamps,  the  main  switch 
should  not  be  closed  until  the  machine  is  developing  the  correct 
voltage. 

In  stopping  a  generator,  the  load  is  first  removed  and  the 
engine  driving  the  generator  is  then  stopped  in  the  usual  manner. 

Care  of  Motors  and  Generators. — It  is  very  important  to  keep 
electric  machines  clean  and  all  insulation  free  from  dust  and  gritty 
substances. 

The  commutator  should  be  kept  clean  and  allowed  to  assume 
a  glaze  while  running.  Oil  should  not  be  used  on  commutators, 
as  it  chars  under  the  brushes,  forming  a  film  between  commutator 
bars  which  may  cause  a  short-circuit. 

The  commutator  brushes  should  be  kept  in  good  shape.  They 
should  be  removed  frequently  for  inspection  and  cleaning,  and 
if  necessary  should  be  filed.  To  remove  grease  or  dirt  the  brushes 
should  be  soaked  in  gasoline. 

If  the  brushes  are  not  properly  trimmed  or  are  in  poor  condi- 
tion the  commutator  will  present  a  bright  coppery  appearance 
and  will  be  found  rough  when  felt  by  hand.  If  in  very  poor 
condition,  the  commutator  may  have  to  be  turned  down. 

Sparking  at  commutators  usually  will  occur  if  brushes  are 
improperly  set,  commutator  is  rough,  machine  is  overloaded, 
short-circuited  or  grounded. 

Heating  of  armatures  may  be  caused  by  the  short-circuiting 
of  some  of  the  armature  coils  or  by  too  great  a  load.  A  short- 
circuited  armature  coil  usually  can  be  detected  by  its  high  tem- 
perature. If  a  greater  part  of  the  coils  are  short-circuited  the 
determination  becomes  more  difficult  and  sensitive  instruments 
have  to  be  used. 


270  FARM  MOTORS 

A  hot  bearing  also  will  cause  the  heating  of  the  armature,  and 
this  usually  can  be  detected  and  remedied. 

Problems:  Chapter  X 

1.  What  is  meant  by  the  following  electrical  terms:  voltage,  amperes, 
kilowatts,  electrical  horsepower,  ohms? 

2.  Calculate  the  current  consumed  by  a  25-watt  tungsten-filament  lamp, 
which  is  operated  on  a  110-volt  circuit. 

3.  State  and  explain  the  application  of  Ohm's  law. 

4.  How   does   the    current   consumed   by   the   tungsten-filament   lamp 
compare  with  that  consumed  by  the  carbon-filament  lamp  of  the  same 
candlepower? 

6.  Explain  the  Brown  and  Sharpe  wire  gage  and  calculate  the  size  of  rub- 
ber-covered wire  required  to  carry  a  current  of  10  amp.  Neglect  transmis- 
sion losses. 

6.  Calculate  the  power  of  a  gasoline  engine  required  to  drive  an  electrical 
generator  of  3  kw.  capacity. 

7.  Calculate  the  horsepower  of  a  gasoline  engine  required  to  supply  twelve 
40- watt  tungsten-filament  lamps  and  four  16-cp.  carbon-filament  lamps. 
Allow  25  per  cent,  for  losses. 

8.  If  an  arc  lamp  consumes  5  amp.  at  110  volts,  calculate  its  resistance. 

9.  What  is  a  primary  battery?  a  storage  battery? 

10.  Explain  the  composition  of  the  dry  cell.     In  which  respects  does  the 
construction  of  the  dry  battery  differ  from  the  ordinary  wet  battery? 

11.  What  are  the  fundamental  parts  of  a  lead  storage  battery? 

12.  Give  directions  for  testing  a  storage  battery. 

13.  How  distinguish  the  positive  and  negative  plates  of  a  lead  storage 
battery? 

14.  How  are  storage  batteries  rated? 

16.  In  which  respects  does  the  Edison  battery  differ  from  the  lead  storage 
battery? 

16.  What  is  the  voltage  of  a  storage  battery  of  32  Edison  cells  connected  in 
series?     How  much  greater  would  the  voltage  of  this  battery  be  if  made  up  of 
lead  cells? 

17.  How  should  a  battery  of  six  dry  cells  be  connected  to  give  the  greatest 
voltage?     Calculate  the  approximate  voltage  of  the  battery. 

18.  How  should  storage  batteries  be  connected  to  give  the  greatest  voltage 
and  as  much  current  as  possible?     Illustrate  by  sketch. 

19.  When  should  the  multiple  system  of  battery  connection  be  used? 

20.  The  reading  .of  an  ammeter  connected  in  series  with  a  coil  is  18  amp. 
If  the  voltage  between  the  terminals  is  7  volts,  calculate  resistance  of  coil. 

21.  Calculate  the  current  which  will  flow  through  a  resistance  of  440  ohms, 
the  voltage  between  terminals  being  110. 

22.  Can  alternating  current  be  measured  by  direct-current  instruments? 
Give  reasons  for  your  answer. 


GENERATORS,  ELECTRIC  MOTORS,  ETC.        271 

23.  Give  clear  abstract  of  Bulletin  No.  1  of  the  Kansas  State  Agricultural 
College  Engineering  Experiment  Station  and  of  Bulletin  No.  25  of  the  Iowa 
State  College  Engineering  Experiment  Station.     These  bulletins  deal  with 
illumination  for  farm  homes. 

24.  Give  directions  for  installing  electric  motors. 

25.  Give  directions  for  starting  a  shunt-wound  direct-current  motor. 


CHAPTER  XI 
ANIMAL  MOTORS 

Animals  used  in  the  United  States  as  farm  motors  include 
mainly  horses,  mules,  and  oxen.  Sheep,  dogs,  goats,  camels, 
water-buffalos,  elephants,  reindeers,  and  caribous  are  used  to  a 
limited  extent  in  other  countries.  The  power  developed  by 
horses  and  mules  on  American  farms  exceeds  that  generated  by 
all  other  forms  of  farm  motors,  animal  as  well  as  mechanical. 

The  Horse. — Of  all  animal  motors  the  horse  is  the  most  impor- 
tant for  farm  use.  The  horse  is  intelligent,  willing,  a  fast  walker 
as  compared  with  other  draft  animals,  and  self-reproducing. 
Large-sized  hoofs  make  it  possible  for  horses  -to  be  used  on 
comparatively  soft  ground. 

Selection  of  a  Draft  Horse. — Dr.  H.  J.  Waters,  in  his  book, 
"The  Essentials  of  Agriculture,"  l  gives  the  following  rules  for 
judging  draft  horses: 

"Size  and  weight  are  determining  factors  in  the  classification  of 
draft  horses.  To  belong  to  this  class  a  horse  should  weigh  1,600  Ib. 
or  more  and  should  be  at  least  15.2  hands  high.  Value  increases  with 
size,  other  things  being  equal. 

"The  draft  horse  should  be  deep,  wide,  and  compact  of  body,  and 
should  carry  his  weight  uniformly.  The  top  line  should  be  strong  and 
short,  while  the  under  line  should  be  long  and  straight.  Quality  is  an 
essential  of  good  service.  It  is  indicated  by  fine  hair;  clean,  strong 
joints  clean,  flat  legs;  and  tough,  firm  feet.  The  head  should  be 
clearly  defined  and  bony  in  appearance,  with  good  width  of  forehead. 

"The  head  should  be  proportionate  to  the  body,  neither  too  large 
nor  too  small,  with  clean  muzzle,  medium  ear,  bright  eye,  broad  fore- 
head, and  a  clean  throatlatch.  A  thick  throatlatch  usually  indicates 
'poor  wind/  The  neck  should  be  of  medium  length,  with  a  slight  crest, 
and  should  be  well-muscled.  The  shoulders  should  be  long  and  slop- 
ing, in  order  to  give  breaking  surface  for  the  collar  and  to  lessen  the 
concussion  of  hard  streets.  Good  muscular  development  of  arm  and 
forearm  is  essential.  The  withers  should  be  of  medium  height.  A 
back  with  close  coupling  and  with  a  long,  heavy-muscled  croup  is  a 

1  H.  J.  WATERS,  "The  Essentials  of  Agriculture,"  Ginn  &  Co.,  1915. 

272 


ANIMAL  MOTORS  273 

conformation  representing  the  greatest  strength.  Long,  well-sprung 
ribs  with  a  deep  and  well-filled  rear  flank  make  room  for  a  well-developed 
digestive  apparatus  and  strong  vital  organs.  Muscular  development 
of  the  hind  quarters  is  essential.  The  draft  horse  should  stand  squarely 
on  its  legs.  The  legs  should  be  clean,  with  bone  of  good  size  and  with 
strong  joints.  The  pastern  should  be  sloping,  and  the  hocks  should 
be  large  and  of  regular  shape. 

"Constitution  is  indicated  by  a  deep,  broad  chest,  together  with  a 
well-sprung  rib,  a  deep  body,  bright  eyes,  and  great  energy*. 

"The  action  of  draft  horses  is  important.  The  stride  at  the  walk 
and  trot  should  be  long,  straight,  and  regular.  Correct  conformation 
gives  elasticity  to  the  walk  and  the  trot  in  all  horses.  Reasonable 
grace  and  style  of  carriage  are  demanded." 

When  pulling  a  heavy  load  there  is  a  tendency  for  the  horse 
to  lift  his  front  feet  off  the  ground.  This  tendency  decreases 
as  the  weight  of  the  horse  increases.  The  distribution  of  weight 
is  also  an  important  consideration. 

The  hock  muscles  should  receive  careful  attention,  as  such 
muscles,  when  deficient  in  strength,  limit  the  ability  of  a  horse  to 
pull  a  load.  The  wider  the  hock,  the  more  leverage  the  muscle 
will  have. 

The  other  essentials  for  a  draft  horse  are  broad  muscular 
breast,  heavy  muscles  of  arm  and  forearm,  large  well-supported 
knees,  short  cannons,  strong  fetlocks  and  pasterns,  and  large, 
sound  feet. 

Capacity  and  Power  of  Draft  Animals. — The  average  draft 
horse  can  exert  from  day  to  day  a  pull  from  one-eighth  to  one- 
tenth  of  his  weight  for  about  10  hr.  a  day,  if  walking  at  the  nor- 
mal rate  of  about  2J£  miles  per  hour.  The  skeleton  and  muscular 
development  of  the  horse  is  such  that  he  is  adapted  to  pulling 
loads.  A  horse  is  capable  of  pulling  a  load  several  times  his  own 
weight,  while  his  carrying  capacity  is  only  a  fraction  of  the  weight 
of  his  body. 

A  draft  horse  weighing  1,600  lb.,  when  pulling  a  load  one- 
tenth  of  his  weight  at  the  rate  of  2  miles  per  hour,  will  develop : 

Draft  X  distance  traveled  per  minute 
Horsepower  =  33,000 

In  the  case  of  the  above  problem,  the  draft  of  the  horse  is 
/I  £t/~\r^\ 
(  \Q   }  =160  lb.,  the  distance  traveled  is  2  miles  per  hour  or 

18 


274  FARM  MOTORS 


(2  X  5,280)  ==  10,560  ft.  per  hour,  or  p    =  176  ft.  per  min- 

160  Ib.  X  176  ft.  per  minute 
ute.     The  horsepower  developed  =  -  -  Q0  ftnn 

OOjUUU 

=  0.853. 

The  weight  of  the  ordinary  draft  horse  usually  is  less  than 
1,600  Ib.  and  the  average  power  developed  by  a  draft  horse 
when  worked  at  normal  rate  is  about  %  hp.  Horses  can  develop 
power  much  in  excess  of  the  normal  amount  for  short  periods  of 
time.  Tests  have  demonstrated  that  for  very  short  periods  of 
time  a  good  draft  horse  can  develop  as  much  as  4  or  5  hp.  This 
ability  of  the  horse  to  stand  overloads  may  be  advantageous  in 
emergencies,*  but  must  not  be  taken  advantage  of  too  frequently. 

Power  being  the  rate  of  doing  work,  an  increase  in  the  speed 
of  a  horse  should  be  accompanied  by  a  reduction  in  the  load  to  be 
carried  by  the  animal.  On  the  other  hand,  if  the  working  day  is 
reduced  from  10  to  4  or  5  hr.,  the  load  may  be  increased.  Thus 
the  capacity  for  tractive  effort  decreases  as  the  speed  and  the 
time  increase. 

The  power  developed  by  a  horse  when  trotting  or  galloping 
is  decreased  by  the  fact  that  the  heart  action  is  greatly  increased 
and  heat  is  lost  by  the  evaporation  of  water  through  the  skin  and 
lungs,  thus  leaving  only  a  small  portion  of  the  energy  in  the  fuel 
available  for  work;  much  energy  is  used  up  non-productively 
also  in  the  horse's  raising  his  own  body  in  galloping. 

It  is  not  advisable  to  work  horses  of  unequal  size  and  weight 
together.  Horses  should  be  chosen  similar  in  temperament, 
type,  and  weight. 

It  is  not  desirable  to  have  horses  work  too  close  together  or 
under  conditions  which  may  result  in  the  draft  animal  fretting. 
Fretting  uses  up  energy  which  should  be  made  available  for  useful 
work. 

Hip  straps,  if  too  short,  will  reduce  the  capacity  of  a  horse  for 
work,  as  the  animal  with  short  hip  straps  carries  part  of  the  load. 

Other  factors  which  influence  the  power  developed  by  draft 
animals  are  the  grip  on  the  surface  of  the  road  and  the  angle 
of  trace.  The  angle  of  trace  is  the  angle  between  the  tugs  and 
the  surface  of  the  ground.  This  angle  should  be  considered  with 
reference  to  the  comfort  of  the  horse  and  the  least  draft. 


ANIMAL  MOTORS  275 

Selection  of  Feed  for  the  Horse. — The  selection  of  proper  feed 
is  as  important  to  the  successful  maintenance  and  use  of  a  horse 
as  is  the  securing  of  proper  fuel  and  of  good  lubricating  oil  for 
operating  a  steam  traction  engine  or  an  oil  engine. 

The  feed  supplied  to  the  animal  must  contain  sufficient 
nutritive  material  for  building  up  the  bodies  of  young  animals, 
as  in  growth  and  for  repairing  the  tissues  of  the  bodies  of  animals 
of  all  ages  which  are  constantly  being  worn  out  by  work  or  other 
exercise.  The  feed  must  also,  in  addition  to  accomplishing  these 
purposes,  be  capable  of  developing  energy  necessary  for  carrying 
on  the  complex  processes  within  the  animal  body,  as  well  as  the 
energy  for  performing  external  work  as  a  motor.  The  horse  is 
fed  properly,  if  constant  body  weight  is  maintained  while  doing 
normal  work.  Loss  in  weight  means  insufficient  or  improperly 
selected  food  or  overwork,  while  a  gain  in  weight  indicates  unnec- 
essary expenditure  of  food,  unless  it  be  to  overcome  the  effect 
of  temporary  overwork.  In  general,  stationary  body  weight  is  a 
safe  guide  in  the  feeding  of  work  horses,  but  in  practice  it  fre- 
quently happens  that  horses  are  worked  so  hard  for  short  periods, 
as  during  plowing  and  seeding  season,  or  harvest  season,  that  it  is 
not  possible  to  supply  enough  nutrients  during  such  period  to 
maintain  a  constant  body  weight,  or  to  prevent  the  horse  from 
losing  weight.  Such  a  period  usually  is  followed  by  one  of  com- 
parative idleness,  as  in  the  winter,  when  the  horse  is  fed  liberally 
enough  to  store  fat  on  its  body  to  be  used  as  a  source  of  energy 
during  the  rush  season  that  is  to  follow. 

Fat  is  the  most  concentrated  form  of  animal  food  known  and 
contains  about  2J4  times  as  much  energy  per  unit  of  weight  as 
the  starches  and  sugars. 

When  feed  is  abundantly  nutritious,  animals  store  up  fat 
with  which  to  protect  themselves  against  the  cold,  or  to  supply 
the  energy  to  enable  them  to  travel  to  new  sources  of  nourish- 
ment when  the  old  supply  fails,  or  to  new  sources  of  water. 

The  feed  supplied  for  building  up  and  for  repairing  the  body 
and  tissue  must  contain  certain  nutrients.  These  nutrients  are 
protein,  mineral  matter,  carbohydrates,  and  water. 

Protein  is  the  term  supplied  to  a  group  of  organic  substances 
of  which  casein  of  milk,  white  of  egg,  and  the  gluten  of  wheat  are 


276  FARM  MOTORS 

examples.  The  protein  forms  the  basis  of  the  living  tissues,  is  a 
source  of  growth  of  animals,  and  is  the  material  used  principally  in 
repairing  the  waste  of  the  body.  Protein  may  be  also  the  source 
of  energy,  but  there  are  many  cheaper  and  more  efficient  sources 
of  energy,  and  protein  is  too  costly  to  be  used  principally  for  this 
purpose.  There  is,  however,  no  substitute  for  protein  as  a  source 
of  growth,  or  as  a  means  of  repairing  the  worn  body  tissues. 

Mineral  matter,  or  ash,  is  the  inorganic  material  present  in 
different  feeding  stuffs.  The  mineral  matter  in  the  food  supplies 
material  principally  for  the  formation  of  the  skeleton,  hoof,  and 
horn,  but  is  necessary  also  for  the  production  of  soft  tissues. 
Most  feeds  contain  plenty  of  mineral  matter  to  satisfy  all  the 
requirements  of  work  animals. 

The  carbohydrates  are  the  principal  source  of  energy  and  are 
chiefly  used  in  building  up  the  body  and  fat,  which  is  simply 
stored  energy.  Familiar  forms  of  carbohydrates  are  the  sugars, 
starches,  oils  and  fats,  and  woody  fibers. 

The  animal  body  requires  protein,  mineral  matter,  and  carbo- 
hydrates in  definite  proportions,  depending  upon  the  kind  of 
animal,  its  age,  and  what  the  animal  is  doing.  A  young,  active 
colt,  for  example,  requires  a  more  generous  supply  of  all  of  these 
materials  in  proportion  to  its  body  weight  than  a  mature  horse. 
That  is  ideal,  because  the  colt  is  growing  rapidly  and  requires  for 
the  support  of  this  process  much  protein  and  mineral  matter.  ]  t 
is  also  active  and  requires  considerable  fuel,  or  carbohydrates, 
to  supply  the  energy  expended.  A  horse  that  is  hard  at  work 
will  require  more  food  and  a  greater  proportion  of  protein  and 
mineral  matter  than  will  one  that  is  idle,  because  there  is  greater 
expenditure  of  energy,  and  because  activity  causes  a  greater  wear 
upon  the  body  tissue.1 

The  Mule. — The  mule  is  tougher  and  hardier  than  the  horse, 
is  less  subject  to  disease  or  inflammation  from  slight  injuries, 
may  be  handled  by  less  intelligent  farm  labor,  and  is  better  able 
to  take  care  of  itself  than  is  the  horse. 

The  mule  is  used  very  largely  as  a  work  animal  in  the  Southern 
States. 

The  Ox. — The  ox  has  much  endurance  and  is  not  excitable, 

1  The  composition  of  various  feeds  can  be  found  in  Farmer's  Bulletin  No. 
170  of  the  United  States  Department  of  Agriculture. 


ANIMAL  MOTORS  277 

but  is  slow  and  unintelligent,  and  has  little  spirit.  Oxen  are 
seldom  used  at  the  present  time,  but  their  use  is  increasing  in  some 
regions,  because  of  the  steadily  increasing  cost  of  horses. 

Cost  of  Animal  Power. — The  cost  of  maintaining  a  horse, 
when  there  are  taken  into  consideration  feed,  labor  in  caring, 
depreciation  of  horse,  depreciation  of  harness,  shoeing,  shelter 
and  interest  on  the  investment,  varies  from  $100  to  $150  per 
year. 

The  cost  of  feed  per  horsepower  per  hour  with  animal  motors 
has  been  estimated  at  about  6  cts.  The  total  cost  of  power,  with 
animal  power,  per  horsepower  per  hour  when  considering  the  to- 
tal cost  of  maintaining  the  animal  has  been  estimated  at  about 
12  cts. 

Problems:  Chapter  XI 

1.  What  animal  motors  are  used  in  the  United  States? 

2.  How  does  the  power  developed  by  animal  motors  compare  with  that 
developed  by  all  other  forms  of  motors  on  American  farms?     (See  Transac- 
tions American  Society  of  Agricultural  Engineers,  vol.  ix.) 

3.  Give  directions  for  determining  the  suitability  of  a  draft  horse  for  work 
as  a  farm  motor. 

4.  Make  a  study  of  the  distribution  in  the  weight  of  a  draft  horse  and 
report  how  this  will  affect  his  ability  to  pull  a  load. 

6.  What  is  the  normal  capacity  of  a  draft  horse  and  what  is  his  maximum 
pulling  capacity? 

6.  A  draft  horse  weighing  1,600  Ib.  will  develop  how  much  power  when 
pulling  160  Ib.  and  at  the  rate  of  2^  miles  per  hour? 

7.  A  farm  horse  weighing  1,200  Ib.  pulls  a  load  of  120  Ib.  at  the  rate  of  2 
miles  per  hour.     How  much  power  will  this  horse  develop? 

8.  What  is  the  relation  between  the  capacity  for  tractive  effort  and  the 
speed  at  which  a  horse  is  travelling? 

9.  Report  in  detail  how  the  angle  of  trace  affects  the  capacity  of  a  draft 
animal. 

10.  What  determines  the  proper  feed  for  draft  animals? 

11.  Give  rations  for  a  draft  horse. 

12.  Compare  the  horse  and  the  mule  as  draft  animals. 


CHAPTER  XII 
MECHANICAL  TRANSMISSION  OF  POWER 

While  the  transmission  of  power  by  electric  means  is  advanc- 
ing rapidly,  it  is  probable  that  for  some  time  to  come  power  from 
one  machine  to  another  will  be  transmitted  by  mechanical  means. 

Mechanical  transmission  of  power  between  different  machines 
may  be  accomplished  by  means  of: 

1.  Belts. 

2.  Chains. 

3.  Ropes  and  cables. 

4.  Friction  gearing. 

5.  Toothed  gearing. 

6.  Shafting. 

To  the  above  list  should  be  added  cams,  eccentrics,  connect- 
ing rods,  cranks  and  levers  as  means  for  transmitting  power  to 
the  various  parts  of  the  same  machine. 

Belts. — One  of  the  most  common  methods  of  transmitting 
power  is  by  means  of  leather,  rubber,  canvas,  or  composition 
belting.  On  account  of  slipping,  the  transmission  of  power 
with  belts  is  not  positive  as  is  the  case  with  gears. 

The  simplest  arrangement  is  to  have  the  belt  connect  two  pul- 
leys, one  of  which  is  the  driver  and  the  other  is  the  driven.  The 
belt  may  be  open  or  crossed.  In  the  first  case  the  two  pulleys 
turn  in  the  same  direction.  Connecting  two  pulleys  with  a 
crossed  belt  reverses  the  direction  of  the  driven. 

The  power  transmitted  by  a  belt  depends  upon  the  adhesion 
between  the  belt  and  the  pulley.  For  indoor  work  and  under 
reasonably  dry  conditions,  leather  has  proved  to  be  the  most 
satisfactory  and  reliable  material  for  belts.  It  is,  however,  the 
most  expensive  and  its  use  cannot  be  recommended  for  outside 
work  in  inclement  weather. 

Leather  Belts. — Leather  belts  are  made  up  of  short  strips 
of  oak-tanned  leather,  each  strip  varying  from  44  to  60  in.  in 
length.  Before  being  tanned  for  belting  purposes  the  head,  neck, 
belly  and  tail  portions  of  the  hide  are  trimmed  off.  The  remain- 

278 


MECHANICAL  TRANSMISSION  OF  POWER      279 

der  of  the  hide  is  divided  into  three  portions  from  which  the 
different  grades  of  belting  are  secured.  The  best  grade  of  belting 
comes  from  the  center  piece  of  the  hide,  after  a  strip  is  cut  off 
crosswise  from  the  shoulders.  The  second  grade  comes  from  the 
flanks,  and  the  poorest  grade  from  the  shoulders. 

Leather  belting  is  made  of  single  thickness,  and  is  designated  as 
single-ply,  or  single-belt.  Double-ply  belting  is  made  by  con- 
necting the  flesh  sides  of  two  thicknesses  of  leather. 

The  cost  of  double  belting  is  just  twice  that  of  single  belting, 
but  it  has  been  found  that  it  will  transmit  twice  as  much  power 
and  will  last  more  than  twice  as  long  as  single  belting.  Owing 
to  the  greater  stiffness  of  double  belting  it  will  not  conform  to  the 
surface  of  the  pulley  as  readily  as  a  single  belt,  and  its  use  is  lim- 
ited by  the  size  of  the  pulley.  Double  belts  generally  are  not  used 
on  pulleys  less  than  10  in. 

Rubber  Belts. — These  consist  of  one  or  more  layers  of  cotton 
duck  alternating  with  layers  of  vulcanized  rubber.  The  adhesion 
of  rubber  belts  is  somewhat  better  than  that  of  leather  belts. 
Rubber  belts  also  will  stand  heat,  cold  and  moisture  better  than 
leather  belts.  The  life  of  a  rubber  belt  is  much  shorter  than  that 
of  a  leather  belt  and  the  coating  of  rubber  is  easily  ruined  by  the 
application  of  oil. 

Canvas  Belts. — Canvas  belts  are  lighter  than  rubber  belts. 
They  are  well-adapted  for  saw  mills  or  for  farm  machinery  where 
the  belt  is  exposed  to  the  weather.  Canvas  belts  stretch  and  con- 
tract with  temperature  changes  and  are  not  durable.  Painting 
improves  canvas  belts. 

Care  of  Belts. — Leather  belts  must  be  kept  clean  and  free  from 
dust,  dirt  and  oil.  Dampness  will  loosen  the  cement  which  is 
used  in  building  up  the  belt.  Some  manufacturers  have  now  a 
process  of  waterproofing  leather  belts,  but  this  has  not  been 
extensively  tried  out. 

Most  preparations  called  "belt  dressing"  contain  rosin  and  are 
injurious  to  leather.  If  it  is  necessary  to  soften  a  leather  belt, 
neat's-foot  oil,  tallow,  or  castor  oil  should  be  used. 

The  hair  side  of  a  leather  belt  should  be  run  next  to  the  pulley, 
as  this  is  the  weaker  side,  and  being  smoother  than  the  flesh  side 
will  adhere  much  better  to  the  pulley. 

If  possible,  machinery  should  be  so  placed  that  the  direction 


280 


FARM  MOTORS 


of  the  belt  motion  is  from  the  top  of  the  driving  to  the  top  of 
the  driven  pulley,  when  the  sag  will  increase  the  arc  of  contact. 

Rubber  belts  should  run  with  the  seam  side  out,  and  not  next 
to  the  pulley.  All  animal  greases  and  oils  should  be  kept  away 
from  rubber  belts.  Boiled  linseed  oil  may  be  applied,  but  this 
should  be  done  sparingly. 

Belts  will  hold  better  when  the  pulleys  are  at  long  distances 
apart.  Two  pulleys  connected  by  a  belt  should  be  spaced  far 
enough  apart  so  as  to  allow  of  a  gentle  sag  to  the  slack  side  of 
the  belt  when  in  motion.  This  distance  will  be  10  to  15  ft.  for 
narrow  belts  and  small  pulleys.  In  the  case  of  wide  belts  work- 
ing on  large  pulleys  the  distance  between  driver  and  driven 


Pulley  Side  of  Belt 


Outside  of  Belt 


FIG.  273.— Belt  lacing. 

should  be  at  least  20  ft.  If  too  great  a  distance  is  used,  the  extra 
cost  of  the  belt  will  be  wasted  and  the  extra  weight  of  the  belt 
will  produce  unsteady  motion  and  great  friction  in  the  bearings. 

Method  of  Lacing  Belts. — The  strength  of  the  belt  depends  not 
only  on  the  quality  of  the  material  from  which  it  is  made,  but 
also  on  the  method  used  in  connecting  the  ends.  The  ideal 
joint  is  a  cement  joint.  Such  a  joint  should  be  made  only  after 
the  ends  of  a  belt  have  been  stretched  in  position  over  pulleys. 

Lacing  made  of  rawhide  is  most  commonly  used.  Metallic 
wire  lacing  also  will  give  good  results  if  the  lace  wire  is  hammered 


MECHANICAL  TRANSMISSION  OF  POWER      2S1 

below  the  surface  of  the  leather  so  as  to  prevent  excessive  wear  on 
the  lace,  and  if  care  is  taken  not  to  have  two  wires  cross  each  other 
on  the  pulley  side  of  the  belt.  Wire  lacing  makes  a  less  clumsy 
joint  and  does  not  decrease  the  strength  of  the  belt  on  account  of 
large  holes  as  does  rawhide  lacing. 

To  cement  a  belt,  a  lap  joint  generally  equal  to  the  width  of  the 
belt  is  made  by  beveling  the  two  ends,  applying  glue  and  then 
clamping  the  two  ends  together  in  the  required  position. 

Before  a  belt  is  laced  the  two  ends  should  be  made  absolutely 
square,  otherwise  the  belt  will  tend  to  run  off  the  pulleys.  One 
method  of  lacing  a  belt  is  illustrated  in  Fig.  273. 

Other  methods  of  connecting  the  ends  of  a  belt  are  by  means  of 
belt  fasteners,  rivets,  staples  and  sewing.  These  methods  are  not 
recommended,  as  they  will  pull  out  in  time  and  leave  the  belt 
ends  ragged. 

Pulleys. — Pulleys  are  made  of  iron, 
pressed  steel,  wood  and  paper.  Pulleys  are 
either  solid  (Fig.  274)  or  split  (Fig.  275). 
Large  pulleys  are  usually  of  the  split  type. 

Pulleys  designed  to  transmit  power  by 
belts  usually  are  crowned;  that  is,  the 
rim  is  rounded,  so  that  the  diameter  is 
greater  at  the  middle.  When  crowned 
pulleys  are  used,  the  -belt  will  remain  at 
the  center  of  the  pulley  and  will  not  run 

ce       on,          -j^      f  XL  A-  e  FIG.  274.— Solid  pulley. 

on.     The  width  of  the  acting  surface  or 

face  of  a  pulley  always  should  be  greater  than  that  of  the  belt. 
In  order  to  be  able  to  start  and  to  stop  the  driven  pulley  with- 
out interfering  with  the  driver,  a  combination  of  tight  and  loose 
pulleys  is  often  used.  In  this  case  one  pulley  is  fastened  to  the 
shaft  and  transmits  motion,  while  the  other  is  loose  on  the  shaft. 
The  driving  shaft  carries  a  pulley  which  has  a  width  equal  to 
that  of  the  tight  and  the  loose  pulleys  put  together.  The  belt 
when  in  motion  can  be  shifted  so  that  it  will  run  over  the  tight  or 
over  the  loose  pulley,  thus  throwing  machinery  into  or  out  of  gear. 
Where  tight  and  loose  pulleys  are  employed,  or  in  any  case  where 
the  belt  may  be  shifted,  the  pulleys  are  straight;  that  is,  are  built 
without  crowning,  in  order  that  the  belt  may  be  moved  easily 
from  one  pulley  to  the  other. 


282 


FARM  MOTORS 


The  average  leather  belt  will  not  transmit  its  maximum  force 
on  account  of  slipping  on  the  pulleys.  The  adhesion  between 
the  belt  and  the  pulley  can  be  increased  by  covering  the  pulley 


FIG.  275.— Split  pulley. 


FIG.  276.— Stepped 
pulleys. 


FIG.  277. — Quarter-turn 
belt. 


with  leather.  This  method  of  increasing  the  power  transmitted 
should  be  used  only  in  emergencies.  A  well-designed  drive  with 
the  belts  and  the  pulleys  of  proper  size  to  transmit  the  desired 
power  should  not  require  pulley  covering. 


MECHANICAL  TRANSMISSION  OF  POWER       283 

Small  pulleys  are  secured  to  the  shaft  by  means  of  setscrews. 
Large  pulleys  are  fastened  to  the  shaft  by  keys,  or  sometimes  by 
both  keys  and  set  screws. 

Stepped  pulleys  (Fig.  276)  have  several  faces  of  different 
diameters  on  both  the  drivers  AB  and  driven  CD,  for  varying 
the  speed  of  a  shaft  by  means  of  a  shifting  belt. 

Method  of  Calculating  Sizes  of  Pulleys.— If  there  is  no  slip 
in  the  belt,  the  speeds  of  two  pulleys  connected  by  a  belt  will 
vary  inversely  as  the  diameters  of  the  pulleys. 


FIG.  278. — Sprocket  wheels. 

Calling  D  the  diameter  of  the  driver,  d  the  diameter  of  the 
driven,  N  the  revolutions  of  the  driver,  and  n  the  revolutions  of 
the  driven,  the  following  equation  holds: 

DN  =  dn 

(The  product  of  the  diameter  of  the  driver  and  its  revolutions 
must  be  equal  to  the  product  of  the  diameter  of  the  driven  and 
its  revolutions.) 

As  an  illustration:  A  gasoline  engine  running  at  300  r.p.m. 
has  a  belt  pulley  20  in.  in  diameter.     Calculate  the  size  of  the 
driven  pulley  if  it  is  to  run  at  600  r.p.m. 
From  the  above  equation 

20  X  300 
d  =  —600—  =  10  m' 


284- 


FARM  MOTORS 


The  above  rule  applies  equally  well  to  gears,  only  the  num- 
ber of  teeth  in  the  gears  is  used  instead  of  the  diameters  of  the 
gears.  For  example,  if  the  driving  gear  running  at  100  r.p.m. 
has  80  teeth,  the  driven  must  have  40  teeth  if  it  is  to  run  at 
200  r.p.m.  and  160  teeth  if  it  is  to  run  half  as  fast  as  the  driver. 

Quarter-turn  Belt. — Sometimes  it  becomes  necessary  to  drive 
by  means  of  a  belt  two  pulleys  which  are  at  or  nearly  at  right 
angles  with  each  other.  If  this  must  be  accomplished  without 
the  use  of  guide  pulleys,  as  shown  in  Fig.  277,  certain  conditions 
are  essential.  If  A  is  the  driver,  the  follower  B  must  be  so  placed, 
that  the  belt  leaving  the  face  of  pulley  A  will  lead  to  the  center  of 
the  face  of  pulley  B  (Fig.  277).  This  means  that  the  belt  must  be 


FIG.  279. — Links  for  chain  drive. 

delivered  from  each  pulley  in  the  plane  of  the  pulley  toward 
which  it  is  running.  If  the  direction  of  motion  of  the  driver  is 
reversed,  the  belt  will  be  thrown  from  the  pulleys. 

Chain  Drives. — Chains  made  of  metal  are  used  to  some  extent 
for  transmitting  power.  The  chains  run  on  sprocket  wheels, 
which  are  provided  with  suitable  projections  (Fig.  278). 

Chain  drives  are  more  positive  than  belt  drives  and  will  operate 
in  damp  places.  The  disadvantages  of  chain  drives  are  that 
they  stretch,  are  noisy  and  are  expensive  to  keep  in  repair.  Fig. 
279  illustrates  links  for  a  chain  drive,  used  in  connection  with 
motors. 

Chains  for  automobiles  usually  are  supplied  with  rollers  to 
reduce  friction. 

Rope  Transmission. — Rope  drives  offer  the  following  advan- 
tages for  power  transmission: 

1.  Power  may  be  transmitted  to  much  greater  distances  than 
is  possible  with  belts. 


MECHANICAL  TRANSMISSION  OF  POWER      285 

2.  Driver  and  driven  can  be  very  close  together. 

3.  Power  can  be  transmitted  more  readily  to  different  floors 
of  a  building.     This  is  advantageous  in  flour  or  cement  mills. 


.      FIG.  280.— Pulley  for  rope  drive. 

4.  Shafts  of  driver  and  driven  can  be  at  any  angle  with  each 
other. 

5.  Drive  is  noiseless. 


FIG.  281.— Rope  drive. 

6.  Loss  by  slipping  is  very  small, 

Hemp  and  cotton  ropes  are  commonly  used,  these  ropes  running 
on  cast-iron  pulleys  (Fig.  280)  which  are  provided  with  grooves 


286  FARM  MOTORS 

upon  their  faces  to  keep  the  ropes  in  place.  Wire  ropes  are  used 
for  the  transmission  of  large  power  over  great  distances,  and  in 
connection  with  hoists,  elevators,  inclined  railways  and  dredging 
machinery. 

In  the  United  States  the  continuous  system  (Fig.  281)  is  most 
commonly  used.  In  this  case  ropes  are  wound  over  the  driving 
pulley  A  and  driven  pulley  B  several  times.  The  traveling  ten- 
sion carriage  C  keeps  the  ropes  on  the  pulleys  at  the  proper  tension. 
This  system  is  especially  well-adapted  for  vertical  and  angle 
drives. 

Another  method  is  to  run  independent  ropes  side  by  side  in 
grooves  of  pulleys  (Fig.  282).  This  system  is  called  the  multi- 


FIG.  282. — Rope  drive. 

pie  system  and  is  used  to  some  extent  for  transmitting  large 
powers,  where  the  shafts  are  very  nearly  parallel.  The  continu- 
ous system  (Fig-.  281)  has  a  much  wider  range  of  application 
than  the  multiple  system. 

Friction  Gearing. — In  the  case  of  friction  gearing  the  driver 
and  driven  are  without  teeth  and  pressed  together,  no  belts  or 
chains  being  used,  and  the  power  transmitted  is  due  to  the  fric- 
tion between  the  surfaces  of  the  two  wheels.  In  order  to  reduce 
the  slipping  to  a  minimum  and  to  prevent  the  pressure  between 
the  two  wheels  from  being  too  great,  one  or  both  of  the  gears  are 
made  of  some  slightly  yielding  material  like  wood,  leather,  or 
paper,  as  shown  in  Figs.  283  and  284.  If  only  one  of  the  gears  is 
made  of  wood  or  paper  and  the  other  of  iron,  the  gear  with  the 
softer  material  must  be  the  driver. 

Friction  gears  are  made  as  spur  gears  (Fig.  283)  if  the  axes 


MECHANICAL  TRANSMISSION  OF  POWER       287 


to  be  connected  are  parallel.     Bevel  friction  gears  (Fig.  284)  are 
used  for  connecting  axes  at  right  angles  to  each  other. 


FIG.  283. — Friction  gears. 

Another  form  of  friction  gears  consists  of  grooves  cut  in  the 
circumference  of  two  wheels,  the  projections  of  one  gear  being 
forced  into  the  grooves  of  the  other. 


FIG.  284. — Friction  gears. 

The  disc  and  roller  constitute  another  form  of  friction  gearing. 
If  the  disc  revolves  at  a  uniform  speed,  the  speed  of  the  roller 
can  be  increased  by  moving  it  away  from  the  center  and  decreased 


288 .  FARM  MOTORS 

by  moving  the  roller  toward  the  center  of  the  disc.  If  the  roller 
is  moved  past  the  center,  its  motion  is  reversed. 

The  friction  drive  as  applied  to  automobiles  (Fig.  140)  works 
on  the  principle  of  the  disc  and  roller.  A  flat-faced  disc  A  is 
attached  to  the  crankshaft  of  the  motor.  The  other  part  con- 
sists of  a  wheel  B  keyed  to  a  shaft  S  parallel  to  the  disc  but  free 
to  move  on  the  shaft.  Speed  changes  and  reversing  can  be  ac- 
complished by  shifting  the  wheel  on  the  face  of  the  disc. 

The  objections  to  friction  gears  are: 

1.  The  drive  is  not  positive,  as  there  always  must  be  some 
slipping. 

2.  The  transmission  of  power  by  friction  gears  produces  ex- 
cessive pressures  on  bearings. 


FIG.  285. — Spur  gear.  FIG.  286. — Rack  and  pinion. 

Friction  gears  are  used  where  the  power  to  be  transmitted  is 
not  very  great  and  where  changes  of  speed  have  to  be  made  while 
the  machinery  is  in  motion,  as  is  often  the  case  with  certain 
machine  tools. 

Toothed  Gearing. — This  form  of  power  transmission  is  em- 
ployed when  a  positive  speed  ratio  is  desired  between  the  driver 
and  the  driven. 

The  projections  of  one  gear  which  mesh  with  those  of  another 
are  called  teeth.  The  term  "cogs"  is  sometimes  applied  to 
teeth  inserted  in  the  wheel  of  another  material  than  that  of  the 
body  of  the  gear. 

Gears  usually  are  made  of  cast  iron.  For  rough  work  the  gears 
are  cast,  while  for  accurate  work  cut  gears,  made  in  a  special 
machine  tool,  are  used.  Noiseless  gears  are  made  of  rawhide, 
compressed  between  brass  or  iron  plates.  Sometimes  one  of  the 


MECHANICAL  TRANSMISSION  OF  POWER       289 


gears  is  provided  with  removable  wooden  teeth  to  decrease 
noise.  Rawhide  .gears  must  not  be  used  in  places  where  they  may 
get  wet  and  must  not  be  lubricated.  For  most  farm  machinery 
cast-iron  gears  are  used. 

Spur  gears  (Fig.  285)  are  used  for  transmitting  power  between 
parallel  shafts.     A  combination  of  a  gear  meshing  with  teeth 


FIG.  287. — Annular  gear. 


FIG.  288.— Bevel  gears. 


cut  on  a  straight  rectangular  piece  (Fig.  286)  is  called  a  rack  and 
pinion.  An  annular  gear  (Fig.  287)  is  a  wheel  with  teeth  cut  on 
the  inside. 


FIG.   289. — Worm  and 
wheel. 


FIG.  290.— Shaft 
collar. 


Bevel  gears  (Fig.  288)  are  used  for  connecting  two  axes  which 
intersect. 

In  the  worm  and  wheel  (Fig.  289)  the  screw-like  action  of  the 
worm  A  revolves  the  wheel  B.  The  worm  and  wheel  is  used  for 
making  fine  adjustments  on  instruments.  It  is  also  employed 
in  connection  with  hoisting  machinery,  as  by  the  proper  propor- 

19 


290 


FARM  MOTORS 


tioning  of  the  screw  great  weights  can  be  lifted  on  a  drum  con- 
nected on  the  same  shaft  with  the  wormwheel.  The  worm  and 
wheel  is  also  found  on  the  steering  mechanism  of  traction  engines, 
as  illustrated  in  Chapter  VII. 

Shafting. — Shafting  is  either  employed  directly  for  transmit- 
ting power  or  is  used  in  connection  with  pulleys  and  gears. 


FIG.  291.— Shaft  coupling. 


FIG.  292.— Clutch 
coupling. 


Shafting  is  made  of  wrought  iron  or  of  steel.  The  better  the 
material  in  the  shafting,  the  more  power  it  will  be  able  to  trans- 
mit. Also,  the  greater  the  speed  at  which  the  shaft  is  run,  the 
more  power  will  it  transmit.  The  torsional  strength  of  a  shaft, 


FIG.  293.— Shaft  hanger. 


FIG.  294.— Bracket. 


or  the  resistance  which  it  offers  to  breaking  by  twisting,  is  propor- 
tional to  the  cube  of  its  diameter. 

To  prevent  a  shaft  from  moving  endwise,  a  collar  (Fig.  290) 
is  fastened  to  the  shaft  by  means  of  setscrews. 

To  fasten  two  lengths  of  a  shaft  end  to  end,  a  coupling  (Fig. 


MECHANICAL  TRANSMISSION  OF  POWER       291 


291)  is  used.  To  be  able  to  fasten  or  separate  two  lengths  of 
shafting  while  they  are  revolving,  a  clutch  coupling  (Fig.  292)  or 
a  friction  clutch,  illustrated  in  another  part  of  the  book,  should 
be  used. 

The  standard  sizes  of  shafting  are  given  in  odd  sixteenths  of 
an  inch,  and  advance  by  eighths.  They  can  be  obtained  from 
Y\  6  in.  up  to  5J^  in.  cold-rolled.  Shafts  above  5J^  in.  usually  are 
turned. 

Shafting  is  suspended  from  hangers  (Fig.  293)  placed  on  beams, 
floors,  or  ceilings.  A  bracket  (Fig.  294)  is  used  for  suspending 
shafting  from  walls.  Hangers  and  brackets  are  provided  with 
bearings  in  which  the  shafting  revolves.  The  collar  (Fig.  290) 
should  be  placed  on  the  shaft  against  the  bearing.  A  sufficient 


^ 


FIG.  295.— Roller  bearing. 


Fia.  296.— Ball  bearing. 


number  of  hangers  or  brackets  should  be  used  to  prevent  the 
shaft  from  bending. 

The  bearings  used  to  carry  shafting  may  be  plain  bearings,  as 
illustrated  in  connection  with  the  various  types  of  motors.  To 
reduce  the  frictional  resistance  of  a  plain  bearing,  a  roller  bearing 
or  a  ball  bearing  is  used.  In  the  roller  bearing  (Fig.  295)  the 
shaft  rolls  on  hardened  steel  rollers,  while  in  the  ball  bearing 
(Fig.  296)  the  shaft  revolves  on  balls  placed  in  suitably  designed 
grooves.  Both  roller  and  ball  bearings  are  expensive  and  diffi- 
cult to  keep  in  good  order. 

In  general,  the  work  which  can  be  accomplished  by  any  motor 
depends  not  only  on  the  quality  of  the  motor,  but  also  on  the 
system  used  for  transmitting  the  power  of  the  motor  to  the 
machines  where  power  is  utilized. 


292  FARM  MOTORS 


Problems:  Chapter  XII 

1.  What  are  the  different  methods  of  transmitting  power? 

2.  Discuss  the  advantages  of  leather,  rubber  and  canvas  belting. 

3.  What  determines  the  spacing  of  pulleys  which  are  connected  by  belts? 

4.  Explain  the  different  methods  used  for  lacing  belts. 

5.  Why  are  pulleys  crowned  if  they  are  to  be  used  for  transmitting  power 
by  belts? 

6.  An  electric  motor  which  runs  at  a  speed  of  1,200  revolutions  per  minute 
is  to  be  used  for  driving  a  line  shaft  at  200  revolutions  per  minute.     If  the 
motor  has  a  7-in.  pulley,  calculate  the  size  of  the  pulley  on  the  line  shaft. 

7.  A  gasoline  engine  which  operates  at  a  speed  of  350  revolutions  per  min- 
ute is  to  drive  the  following  machines:  a  hay  press,  an  ensilage  cutter  and  a 
corn  sheller.     Find  the  best  speeds  at  which  these  machines  should  operate 
and  specify  the  sizes  of  pulleys  on  the  line  shaft  and  on  the  machines  to  be 
driven,  if  the  gasoline  engine  has  a  15-in.  pulley. 

8.  Give  clear  sketch  showing  how  the  pulleys  should  be  placed  for  a  quar- 
ter-turn belt. 

9.  What  are  the  advantages  of  rope  drives,  of  chain  drives? 

10.  Discuss  the  advantages  and  the  disadvantages  of  friction  gearing. 

11.  Explain  the  differences,  using  clear  sketches,  between  an  annular  gear, 
a  bevel  gear,  a  spur-gear  rack,  a  worm  and  wheel. 

12.  (a)  Explain  the  functions  of  the  following  when  used  in  connection 
with  shafting :  collar,  coupling,  hanger. 

(6)  Discuss  the  advantages  and  the  disadvantages  of  roller  and  ball 
bearings 


INDEX 


B 


Action  of  electricity,  236 

Air  required  for  combustion,  20 

Alcohol  denatured,  76. 

fuel,  75-76 
Alternating  current,  249-250 

magneto,  98-100 

Altitude  and  barometric  pressure,  7 
American  windmill,  221-222. 
Ammeter,  256 
Ampere,  236 
Angle  valve,  30 
Animal  motors,  3,  4,  272 

power,  cost  of,  277 
Anthracite  coal,  19 
Armature,  251 

Atwater-Kent  system,  151-152 
Automatic  governors  for  steam  en- 
gines, 52 
Automobile  accessories,  160 

axles,  142-143 

carburetors,  148—149 

chassis,  123-124 

control  system,  146 

ignition,  149-154 

lighting,  160 

lubrication,  154-155 

motors,  124-132 

parts,  123 

radiator,  128 

starters,  155-160 

steering  systems,  143-146 

tires,  147-148 

transmission,  123,  134-139 
Automobiles,    types  compared,  122 

wheels,  147 
Auxiliary     carburetor     air      valve, 

84 
Auxiliary  exhaust  port,  187 


Back-firing,  78 

Balanced  valve,  48 

Ball  bearing,  291 

Barometric  pressure,  7 

Batteries,  239-248 

Baume"  scale,  74-75 

Belt  lacings,  280 

Belts,  278-281 

Bevel  gear  differential,  140-141 

gears,  289 

Bituminous  coal,  19 
Boiler,  22 

classification  of,  23 

cleaning,  40 

feed  pump,  22 

fire-tube,  23 

management  of,  39 

operation,  40 

rating,  39 

setting,  22 

traction     engine    types,     169- 

170 

Brake  horse-power,  10 
Brakes,  146-147. 
Breeching,  21 
British  thermal  unit,  12 
Buckeymobile,  58-59 

C 

Calculation  of  horse-power,  8 
Canvas  belts,  279 

Capacity  of  storage  battery,  242-243 
Carburetors,  78-87 

automobile  types,  148 

auxiliary  air  valve,  83 

concentric  float-feed  type,  82-83 

function  of,  78 

jacketed  types,  85 


293 


294 


INDEX 


Carburetors,  kerosene,  86 

multiple  jet,  85 

pump-feed  type,  80-81 

traction  engine  types,  188-190 
Care  of  belts,  279 

electric  generators,  269 

motors,  269 

gas  engines,  119 

steam  engines,  62-64 

traction  engines,  203-208 

windmills,  233 

Caterpillar  traction  engine,  194-196 
Chain  drives,  284 
Charging  storage  batteries,  243 
Chassis,  123-124 
Chimney  draft,  37 
Chimneys,  21,  37-38 
Circuit  breakers,  259-260 
Classification  of  gas  engines,  66 

generators  and  motors,  252 
Clutches,  132-134,  176-177 
Coal,  19 
Coke,  20 
Combustion,  20 
Commercial  value  of  fuels,  21 
Comparison  of  various  motors,  3 
Compound  steam  engines,  50,  171 

wound  generators,   254 

motors,  255 

Compression  pressures  for  alcohol,  76 
Cone  clutch,  133 
Connecting  electric  motors,  method 

of,  262-263 

Cooling  of  automobile  motors,  128- 
129 

gas  engines,  87-91 

traction  engines,  184-185 
Cost  of  animal  power,  277 

farm  electric  light  plants,  265 

power,  4 

traction  engine  power,  202 
ergines,  181 

•windmill  power,  234 
Creeping-grip  tractor,  194-196 
Crude  petroleum  distillates,  72-75 
Current  required  to  operate  lamps, 
238 


Delco  system,  151-154,  159 
Diesel  cycle,  66 

engine,  103 
Differential,  123 

Differentials  for  automobiles,   139- 
141 

traction  engines,  177-180 
Direct  current  magneto,  97 

currents,  249 
Dome  for  boiler,  23 
Distribution  of  electricity,  255 
Draft  horse,  272-273 
Drawbar  horse-power,  10 
Dry  battery,  241-242 
Dual  ignition  system,  149 
Dutch  windmill,  221 


E 


Eccentric,  43 

Economy  of  traction  engines,  202 
Edison  storage  battery,  245-247 
Efficiency  of  engines,  66 
Eight-cylinder    automobile    motor, 

127 
Electric  automobiles,  122 

condenser,  95 

conductors,  238 

distribution,  255 

generator,  248 

ignition  system,  91-97 

light  plants  for  farms,  265-267 

meters,  256 

Electricity,  action  of,  236 
Ell-head  motor,  131-132 
En-bloc  motor,  127-128 
Energy,  7 

Erecting  windmills,  230-233. 
Expanding  clutch,  133 


Farm  electric  light  plant,  265-267 
Feed  for  horses,  275-276 
pump,  32-34 


INDEX 


295 


Feed-water  heaters,  36,  171,  174 

Firing  methods,  38 

Flash  point  of  gasoline,  73 

kerosene,  73 

Float-feed  carburetor,  82-85 
Floats  for  carburetors,  85 
Force,  6 
Forced   circulation   cooling  system, 

129 

Four-stroke  cycle,  67 
Friction  clutch,  123 

drive,  137-139 

gearing,  286-288 
Front  automobile  axles,  142 
Fuels,  19-21 

for  gas  engines,  71-76 
Furnace,  21 
Fuses,  257-259 


Gage  cocks,  31 

Gases,  6 

Gas  engine,  65 

cooling  system,  87—91 

cycle,  66 

fuels,  71-76 

horizontal  and  vertical,   78— 

79 

ignition  system,  91-97' 
indicator  cards,  68 
lubrication,  104-106 
fuel  mixture,  65,  78 
parts,  76-78 
selection,  111-113 
producers,  65,  72 
traction  engine  ignition,  190 
,       motor,  182-184 

engines,  180 
Gasoline,  72-74 

automobile,  122-165 
engine  uses,  107-111 
feed  systems,  148 
fires,  73 
storage,  73 
Gate  valve,  29 
Globe  valve,  29 


Governing  of  gas  engines,  106-108 
steam  engines,  51-53 
windmills,  225 

Grades  of  coal,  19 

Grates  for  boiler  furnaces,  26 

Gravity  feed  system,  148 

Grease  cups,  55 


II 


Hammer-break  igniter,  93 
Hangers,  291 
Heat,  11 

engines,  2 

of  combustion  of  fuels,  21 

unit,  12 

Heavy  oil  engines,  103 
High-tension  distributor,  150-151 

magneto,  100-101 
Hit-or-miss  governor,  106 
Hitch  for  traction  engines,  208 
Hopper-cooled  engine,  79,  87 
Horizontal  gas  engine,  78 
Horse,  272 
Horse-power,  8 
Hot  air  engine,  2 

tube  ignition,  91 
Hydraulic  ram,  218-219 
Hydrometer,  73,  75,  244 


Ignition,  149-154 

dynamos,  97 

systems,  91-97,  190-191 

timing,  115 
Illuminating  gas,  72 
Impulse  water  motors,  214-216 
Incandescent  lamps,  238 
Indicator  for  steam  engines,  8-9 
Indicated  horse-power,  8 
Inductance  coil,  92,  95-96 
Induction  coil,  95-96 
Injectors,  35 

Installation   of   electric  machinery, 
267 

gas  engines,  113 


296 


INDEX 


Installation  of  steam  engines,  60 

windmills,  230 
Internal  combustion  engine,  65 

efficiency,  66 
Interrupter,  102 


Jacket  water  temperature,  88,  120 
Jump-spark  ignition,  94-97 

K 

Kerosene,  73,  75 

carburetor,  86,  189 

engine,  75 
Kilowatt,  237 


Lacing  belts,  280-281 

Lead  storage  battery,  243-245 

Leather  belts,  278 

Lever  safety  valve,  30 

Lignite  fuel,  19 

Liquids,  6 

Locomobile,  58 

Losses  in   steam  engines,    49 

Low-tension  magneto,  97-100 

Lubrication  for    automobiles,    154- 

155 

gas  engines,  104-106 
steam  engines,  55 
traction  engines,  203-204 


M 


Magneto  alternating  current,  98-100 

direct  current,  97 

high  tension,  100-101 

ignition,  149 

oscillating  type,  99-100 
Magnetos,  97-101 
Make-and-break     ignition    system, 

92-94 

Management  of  automobiles,   160- 
165 


Management  of  boilers,  39-40 
electric  motors,  268-269 
traction  engines,  203-208 

Master-vibrator  system,  149-151 

Matter,  6 

Mechanical  automobile  starters,  159 
equivalent  of  heat,  12 

Mixer  valves,  80-82 

Motion,  6 

Motor  cycles,  163,  166 
definition  of,  1 

Motor-en-bloc,  127-128 

Motors  for  automobiles,  124—128 
gas  traction  engines,  182-188 
steam    traction    engines,     171- 
175 

Mule,  276 

Multiple  disc  clutch,  133 

Multiple-jet  carburetors,  85 

'    N 

Natural  gas,  20,  72 
Non-freezing  mixtures,  91 

O 

Ohm's  law,  237 
Oil  cooling,  90 

cups,  "55 
Oil  engine  efficiency,  66 

engines,  103-104 
Operating  gas  engines,  114-119 

traction  engines,  203-208 
Oscillating  magneto,  99-100 
Otto  cycle,  66 
Ox,  276 


Parts  of  gas  engines,  76-78 

of  gasoline  automobile,  123 
generators  and  motors,  250-251 
traction  engines,  168-169 
windmills,  222 

Peat,  20 

Pelton  water  wheel,  214-215 


INDEX 


297 


Petroleum  fuels,  20 
Pipe  fittings,  27 

grades,  27 

sizes,  27 

Piping  for  boilers,  26 
Piston  valve,  47 
Plain  slide  valve,  44,  47 
Planetary  transmission,  136-137 
Pop  safety  valve,  30 
Poppett  valve,  129-130 
Power,  7 

cost,  4 

of  horses,  273-274 

of  streams,  211-213 

of  traction  engines,  188 

of  windmills,  234 

on  farms,  4 

transmission,'  278 
Pressure,  6 

Pressure-feed  system,  148 
Primary  battery,  240-242 
Priming  of  carburetor,  85 
Producer  gas,  72 
Prony  brake,  10 

Progressive  transmission,  134-135 
Propeller  shaft,  142 
Properties  of  steam,  18 
Pulleys,  281 

Pump-feed  carburetor,  80-82 
Pumps  for  traction    engines,    170- 
173 

Q 

Quarter-turn  belt,  284 


R 


Radiators,  128,  185 
Ram,  hydraulic,  218-219 
Rating  of  boilers,  39 

of  traction  engines,  202-203 
Rear  automobile  axle,  143 
Repairing  traction  engines,  207 
Return  tubular  boiler,  23 
Reversing  mechanisms,  171-175 
Rheostats,  260 


Roller  bearings,  291 
Rope  transmission,  284 
Rotary  valve  motor,  130 
Rubber  belts,  279 


Safety  valves,  30,  40 
Selecting  a  gas  engine,  111-113 

a  horse,  272 

Selective  transmission,  135-136 
Series-wound  generators,  252-253 

motors,  252-253 

Setting  engine  on  dead  centre,  48 
Shafting,  290 
Shunt- wound  generators,  252-253 

motors,  252-253 
Sight-feed      automatic      lubricator, 

56 
Size  of  pulleys,  283 

of  steam  engine,  44 
Sleeve-valve  motor,  130 
Solids,  6 

Sources  of  energy,  1 
Spark  plug,  96 
Specific  gravity,  13—14 
of  alcohol,  76 
of  electrolyte,  244-245 
of  gasoline,  73 
of  kerosene,  75 
of  petroleum  fuels,  74 

heat,  12-14 
Speed  of  traction  engine  motors,  188 

engines,  203 
Spur  gears,  289 
Spur-gear  differential,  141 
Starting  electric  motors,  268 

gas  engines,  116-117 

systems  for  automobiles,  155- 
159 

traction  engines,  205-206 
States  of  matter,  6 
Steam  automobiles,  122 

chest,  43 

engine,  action  of,  2,  42 
care  of,  62-64 
description,  42 


298 


INDEX 


Steam  engine  details,  53 
governors,  51-53 
indicator,  8 
cards,  49 

installation,  60-61 
losses,  49 
size  of,  44 
gages,  31 

generation  theory,  16 
power  plant,  21-23 
properties,  18 
separators,  57 
superheated,  17 

traction  engine  motor,  171-175 
traps,  32 
turbines,  59-60 
Steering  column,  143-145 

of  traction  engines,  176 
Stepped  pulleys,  283 
Storage  batteries,  242-247 
Straw  fuel,  169-171 
Superheated  steam,  17 
Switches,  260-261 


Tee-head  motor,  132 
Temperature,  11 
Theory  of  steam  generation,  16 
Thermometric  scales,  11-12 
Thermo-syphon  cooling  system,  128 
Throttling  gas-engine  governor,  107 
Throttle    control    of    automobiles, 

145-146 

Timers,  101-102 
Tires,  147-148 
Toothed  gearing,  288-289 
Traction  engine  boilers,  169-170 

carburetors,   188-190 

development,  201-202 

differential,  177-180 

governors,  187-188 

hitch,  208 ' 

parts,  168-169 

power  plant,  168 

rating,  202-203 

reversing  gears,  171-175 


Traction  engine  speeds,  203 

transmission,    168,  176-179,  191- 
194 

valve  setting,  207-208 

wheels,  169 

Tractor  cultivator,  200 
Transmission  gears,  134-139, 191-194 

of  power,  278 
Two-stroke    cycle   gas   engines,    66, 

69,  71 
Types  of  traction,  194-196 

of  windmills,  221 


U 


Universal  joint,  141-142 
Uses  of  electric  motors,  263-264 

gas  engines,  108-111 

storage  batteries,  242 
Users  of  traction  engines,  196-201 

windmills,  234-235 


Vacuum-feed  system,  149 
Valve-in-the-head  motor,  131-132 
Valve  gear  types  for  steam  engines,  47 

setting,  48 
Valves,  28-30 

for  automobile  motors,  129-132 
Various  motors  compared,  3 
Vertical  boilers,  25 

gas  engines,  78-79 
Vibrator,  95 
Volt,  236 
Voltmeter,  256 

W 

Water  column,  31 

motor,  211-215 

tube  boiler,  26 

turbines,  216-218 
Watt,  236 

Wattmeter,  257-258 
Wet  cells,  242 
Windmill  brake,  226 


INDEX  299 

Windmill  gearing,  225-226  Wind  wheel,  223 

governor,  225  Wipe  spark  igniter,  93-94 

parts,  222  Wiring  of  batteries,  247-248 

power  cost,  234  of  electric  meters,  257 

rudder,  224  Wood  as  fuel,  19 

towers,  226-230  Work,  7 

uses,  234  Worm  and  wheel,  289 


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